v1.6.0 to fix memory leak bugs

### Release v1.6.0

1. Fix memory leak bugs. Check [memory leak on 'server_version' #17](#17) and [memory leak on MySQL_Connection.MySQL_Packet.buffer #18](#18)
2. Optimize library code by using `reference-passing` instead of `value-passing`
3. Update RP2040 Ethernet-related examples to use SS/CS pin GP17 for ARDUINO_ARCH_MBED similar to arduino-pico core
4. Update `Packages' Patches`

Ethernet/Basic_Insert/Basic_Insert.ino

@@ -0,0 +1,313 @@
+/*********************************************************************************************************************************
+  Basic_Insert.ino
+      
+  Library for communicating with a MySQL or MariaDB Server
+  
+  Based on and modified from Dr. Charles A. Bell's MySQL_Connector_Arduino Library https://github.com/ChuckBell/MySQL_Connector_Arduino
+  to support nRF52, SAMD21/SAMD51, SAM DUE, STM32F/L/H/G/WB/MP1, ESP8266, ESP32, etc. boards using W5x00, ENC28J60, LAM8742A Ethernet,
+  WiFiNINA, ESP-AT, built-in ESP8266/ESP32 WiFi.
+
+  The library provides simple and easy Client interface to MySQL or MariaDB Server.
+  
+  Built by Khoi Hoang https://github.com/khoih-prog/MySQL_MariaDB_Generic
+  Licensed under MIT license
+ **********************************************************************************************************************************/
+
+/*
+  MySQL Connector/Arduino Example : basic insert
+
+  This example demonstrates how to issue an INSERT query to store data in a
+  table. For this, we will create a special database and table for testing.
+  The following are the SQL commands you will need to run in order to setup
+  your database for running this sketch.
+
+  CREATE DATABASE test_arduino;
+  CREATE TABLE test_arduino.hello_arduino (
+    num integer primary key auto_increment,
+    message char(40),
+    recorded timestamp
+  );
+
+  Here we see one database and a table with three fields; a primary key that
+  is an auto_increment, a string, and a timestamp. This will demonstrate how
+  to save a date and time of when the row was inserted, which can help you
+  determine when data was recorded or updated.
+
+  For more information and documentation, visit the wiki:
+  https://github.com/ChuckBell/MySQL_Connector_Arduino/wiki.
+
+  INSTRUCTIONS FOR USE
+
+  1) Create the database and table as shown above.
+  2) Change the address of the server to the IP address of the MySQL server
+  3) Change the user and password to a valid MySQL user and password
+  4) Connect a USB cable to your Arduino
+  5) Select the correct board and port
+  6) Compile and upload the sketch to your Arduino
+  7) Once uploaded, open Serial Monitor (use 115200 speed) and observe
+  8) After the sketch has run for some time, open a mysql client and issue
+     the command: "SELECT * FROM test_arduino.hello_arduino" to see the data
+     recorded. Note the field values and how the database handles both the
+     auto_increment and timestamp fields for us. You can clear the data with
+     "DELETE FROM test_arduino.hello_arduino".
+
+  Note: The MAC address can be anything so long as it is unique on your network.
+
+  Created by: Dr. Charles A. Bell
+*/
+
+#include "defines.h"
+
+#include <MySQL_Generic.h>
+
+// Select the static Local IP address according to your local network
+IPAddress ip(192, 168, 2, 222);
+
+#define USING_HOST_NAME     true
+
+#if USING_HOST_NAME
+  // Optional using hostname, and Ethernet built-in DNS lookup
+  char server[] = "your_account.ddns.net"; // change to your server's hostname/URL
+#else
+  IPAddress server(192, 168, 2, 112);
+#endif
+
+uint16_t server_port = 5698;    //3306;
+
+char user[]         = "invited-guest";              // MySQL user login username
+char password[]     = "the-invited-guest";          // MySQL user login password
+
+char default_database[] = "test_arduino";           //"test_arduino";
+char default_table[]    = "hello_arduino";          //"test_arduino";
+
+String default_value    = "Hello, Arduino!"; 
+
+// Sample query
+String INSERT_SQL = String("INSERT INTO ") + default_database + "." + default_table 
+                 + " (message) VALUES ('" + default_value + "')";
+
+MySQL_Connection conn((Client *)&client);
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial); // wait for serial port to connect
+
+  MYSQL_DISPLAY3("\nStarting Basic_Insert on", BOARD_NAME, ", with", SHIELD_TYPE);
+  MYSQL_DISPLAY(MYSQL_MARIADB_GENERIC_VERSION);
+
+#if !(USE_ETHERNET_PORTENTA_H7)
+
+  MYSQL_LOGERROR(F("========================================="));
+  MYSQL_LOGERROR(F("Default SPI pinout:"));
+  MYSQL_LOGERROR1(F("MOSI:"), MOSI);
+  MYSQL_LOGERROR1(F("MISO:"), MISO);
+  MYSQL_LOGERROR1(F("SCK:"),  SCK);
+  MYSQL_LOGERROR1(F("SS:"),   SS);
+  MYSQL_LOGERROR(F("========================================="));
+
+#if defined(ESP8266)
+  // For ESP8266, change for other boards if necessary
+  #ifndef USE_THIS_SS_PIN
+    #define USE_THIS_SS_PIN   D2    // For ESP8266
+  #endif
+
+    MYSQL_LOGERROR1(F("ESP8266 setCsPin:"), USE_THIS_SS_PIN);
+
+  #if ( USE_ETHERNET || USE_ETHERNET_LARGE || USE_ETHERNET2 || USE_ETHERNET_ENC )
+    // For ESP8266
+    // Pin                D0(GPIO16)    D1(GPIO5)    D2(GPIO4)    D3(GPIO0)    D4(GPIO2)    D8
+    // Ethernet           0                 X            X            X            X        0
+    // Ethernet2          X                 X            X            X            X        0
+    // Ethernet3          X                 X            X            X            X        0
+    // EthernetLarge      X                 X            X            X            X        0
+    // Ethernet_ESP8266   0                 0            0            0            0        0
+    // D2 is safe to used for Ethernet, Ethernet2, Ethernet3, EthernetLarge libs
+    // Must use library patch for Ethernet, EthernetLarge libraries
+    Ethernet.init (USE_THIS_SS_PIN);
+
+  #elif USE_ETHERNET3
+    // Use  MAX_SOCK_NUM = 4 for 4K, 2 for 8K, 1 for 16K RX/TX buffer
+    #ifndef ETHERNET3_MAX_SOCK_NUM
+      #define ETHERNET3_MAX_SOCK_NUM      4
+    #endif
+
+    Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (ETHERNET3_MAX_SOCK_NUM);
+
+  #endif  //( USE_ETHERNET || USE_ETHERNET2 || USE_ETHERNET_LARGE || USE_ETHERNET_ENC )
+
+#elif defined(ESP32)
+
+  // You can use Ethernet.init(pin) to configure the CS pin
+  //Ethernet.init(10);  // Most Arduino shields
+  //Ethernet.init(5);   // MKR ETH shield
+  //Ethernet.init(0);   // Teensy 2.0
+  //Ethernet.init(20);  // Teensy++ 2.0
+  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
+  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet
+
+  #ifndef USE_THIS_SS_PIN
+    #define USE_THIS_SS_PIN   22    // For ESP32
+  #endif
+
+  MYSQL_LOGERROR1(F("ESP32 setCsPin:"), USE_THIS_SS_PIN);
+
+  // For other boards, to change if necessary
+  #if ( USE_ETHERNET || USE_ETHERNET_LARGE || USE_ETHERNET2 || USE_ETHERNET_ENC )
+    // Must use library patch for Ethernet, EthernetLarge libraries
+    // ESP32 => GPIO2,4,5,13,15,21,22 OK with Ethernet, Ethernet2, EthernetLarge
+    // ESP32 => GPIO2,4,5,15,21,22 OK with Ethernet3
+
+    //Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (USE_THIS_SS_PIN);
+
+  #elif USE_ETHERNET3
+    // Use  MAX_SOCK_NUM = 4 for 4K, 2 for 8K, 1 for 16K RX/TX buffer
+    #ifndef ETHERNET3_MAX_SOCK_NUM
+      #define ETHERNET3_MAX_SOCK_NUM      4
+    #endif
+
+    Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (ETHERNET3_MAX_SOCK_NUM);
+
+  #endif  //( USE_ETHERNET || USE_ETHERNET2 || USE_ETHERNET_LARGE  || USE_ETHERNET_ENC )
+
+#elif ETHERNET_USE_RPIPICO
+
+  pinMode(USE_THIS_SS_PIN, OUTPUT);
+  digitalWrite(USE_THIS_SS_PIN, HIGH);
+
+  // ETHERNET_USE_RPIPICO, use default SS = 5 or 17
+  #ifndef USE_THIS_SS_PIN
+    #if defined(ARDUINO_ARCH_MBED)
+      #define USE_THIS_SS_PIN   5     // For Arduino Mbed core
+    #else  
+      #define USE_THIS_SS_PIN   17    // For E.Philhower core
+    #endif
+  #endif
+
+  MYSQL_LOGERROR1(F("RPIPICO setCsPin:"), USE_THIS_SS_PIN);
+
+  // For other boards, to change if necessary
+  #if ( USE_ETHERNET || USE_ETHERNET_LARGE || USE_ETHERNET2 || USE_ETHERNET_ENC )
+    // Must use library patch for Ethernet, EthernetLarge libraries
+    // For RPI Pico using Arduino Mbed RP2040 core
+    // SCK: GPIO2,  MOSI: GPIO3, MISO: GPIO4, SS/CS: GPIO5
+    // For RPI Pico using E. Philhower RP2040 core
+    // SCK: GPIO18,  MOSI: GPIO19, MISO: GPIO16, SS/CS: GPIO17
+    // Default pin 5/17 to SS/CS
+
+    //Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (USE_THIS_SS_PIN);
+
+  #elif USE_ETHERNET3
+    // Use  MAX_SOCK_NUM = 4 for 4K, 2 for 8K, 1 for 16K RX/TX buffer
+    #ifndef ETHERNET3_MAX_SOCK_NUM
+      #define ETHERNET3_MAX_SOCK_NUM      4
+    #endif
+
+    Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (ETHERNET3_MAX_SOCK_NUM);
+
+  #endif    //( USE_ETHERNET || USE_ETHERNET2 || USE_ETHERNET3 || USE_ETHERNET_LARGE )
+
+#else   //defined(ESP8266)
+  // unknown board, do nothing, use default SS = 10
+  #ifndef USE_THIS_SS_PIN
+    #define USE_THIS_SS_PIN   10    // For other boards
+  #endif
+
+  MYSQL_LOGERROR3(F("Board :"), BOARD_NAME, F(", setCsPin:"), USE_THIS_SS_PIN);
+
+  // For other boards, to change if necessary
+  #if ( USE_ETHERNET || USE_ETHERNET_LARGE || USE_ETHERNET2 || USE_ETHERNET_ENC )
+    // Must use library patch for Ethernet, Ethernet2, EthernetLarge libraries
+
+    Ethernet.init (USE_THIS_SS_PIN);
+
+  #elif USE_ETHERNET3
+    // Use  MAX_SOCK_NUM = 4 for 4K, 2 for 8K, 1 for 16K RX/TX buffer
+    #ifndef ETHERNET3_MAX_SOCK_NUM
+      #define ETHERNET3_MAX_SOCK_NUM      4
+    #endif
+
+    Ethernet.setCsPin (USE_THIS_SS_PIN);
+    Ethernet.init (ETHERNET3_MAX_SOCK_NUM);
+
+  #endif  //( USE_ETHERNET || USE_ETHERNET2 || USE_ETHERNET_LARGE || USE_ETHERNET_ENC )
+
+#endif    //defined(ESP8266)
+
+  // Just info to know how to connect correctly
+  MYSQL_LOGERROR(F("========================================="));
+  MYSQL_LOGERROR(F("Currently Used SPI pinout:"));
+  MYSQL_LOGERROR1(F("MOSI:"), MOSI);
+  MYSQL_LOGERROR1(F("MISO:"), MISO);
+  MYSQL_LOGERROR1(F("SCK:"),  SCK);
+  MYSQL_LOGERROR1(F("SS:"),   SS);
+  MYSQL_LOGERROR(F("========================================="));
+
+#endif    // #if !(USE_ETHERNET_PORTENTA_H7)
+
+  // start the ethernet connection and the server:
+  // Use DHCP dynamic IP and random mac
+  uint16_t index = millis() % NUMBER_OF_MAC;
+  // Use Static IP
+  //Ethernet.begin(mac[index], ip);
+  Ethernet.begin(mac[index]);
+
+  MYSQL_DISPLAY1("Using mac index =", index);
+  MYSQL_DISPLAY1("Connected! IP address:", Ethernet.localIP());
+
+  MYSQL_DISPLAY3("Connecting to SQL Server @", server, ", Port =", server_port);
+  MYSQL_DISPLAY5("User =", user, ", PW =", password, ", DB =", default_database);
+}
+
+void runInsert()
+{
+  // Initiate the query class instance
+  MySQL_Query query_mem = MySQL_Query(&conn);
+
+  if (conn.connected())
+  {
+    MYSQL_DISPLAY(INSERT_SQL);
+
+    // Execute the query
+    // KH, check if valid before fetching
+    if ( !query_mem.execute(INSERT_SQL.c_str()) )
+    {
+      MYSQL_DISPLAY("Insert error");
+    }
+    else
+    {
+      MYSQL_DISPLAY("Data Inserted.");
+    }
+  }
+  else
+  {
+    MYSQL_DISPLAY("Disconnected from Server. Can't insert.");
+  }
+}
+
+void loop()
+{
+  MYSQL_DISPLAY("Connecting...");
+
+  //if (conn.connect(server, server_port, user, password))
+  if (conn.connectNonBlocking(server, server_port, user, password) != RESULT_FAIL)
+  {
+    delay(500);
+    runInsert();
+    conn.close();                     // close the connection
+  } 
+  else 
+  {
+    MYSQL_DISPLAY("\nConnect failed. Trying again on next iteration.");
+  }
+
+  MYSQL_DISPLAY("\nSleeping...");
+  MYSQL_DISPLAY("================================================");
+
+  delay(60000);
+}