updated Firmata library to version 2.3.5 and moved to the new library format

Author: Fede85

hardware/arduino/avr/libraries/Firmata/TODO.txt

@@ -15,8 +15,6 @@
  */
 #include <Firmata.h>
 
-byte analogPin;
-
 void stringCallback(char *myString)
 {
     Firmata.sendString(myString);