DS3231-RTC Release

A completely reworked and refractured DS3231 library based on standardized function from time.h.

Platforms

• Arduino IDE
• PlatformIO

Tested on the following Boards:

• ESP8266
• Arduino Nano
• Arduino Nano 33 IOT

Main changes:

• use struct tmfor data holding memory
• use the corresponding time functions to convert into and from struct tm
• cleanup code
• rework code comments
• review Documentation
• add new example DateTime_Constructor_Test