Allow println to send \n and not \r\n

hardware/arduino/avr/cores/arduino/Print.cpp

@@ -125,7 +125,7 @@ size_t Print::print(const Printable& x)
 
 size_t Print::println(void)
 {
-  return write("\r\n");
+  return write(line_ending);
 }
 
 size_t Print::println(const String &s)
@@ -198,6 +198,10 @@ size_t Print::println(const Printable& x)
   return n;
 }
 
+void Print::set_line_ending(const char * ending){
+        line_ending = ending;
+}
+
 // Private Methods /////////////////////////////////////////////////////////////
 
 size_t Print::printNumber(unsigned long n, uint8_t base)

hardware/arduino/avr/cores/arduino/Print.h

@@ -40,11 +40,14 @@ class Print
     int write_error;
     size_t printNumber(unsigned long, uint8_t);
     size_t printFloat(double, uint8_t);
+    const char * line_ending;
   protected:
     void setWriteError(int err = 1) { write_error = err; }
   public:
-    Print() : write_error(0) {}
-
+    Print() : write_error(0) {
+            line_ending = "\r\n";
+    }
+
     int getWriteError() { return write_error; }
     void clearWriteError() { setWriteError(0); }
 
@@ -87,6 +90,8 @@ class Print
     size_t println(const Printable&);
     size_t println(void);
 
+    void set_line_ending(const char * ending);
+
     virtual void flush() { /* Empty implementation for backward compatibility */ }
 };