Adding New Classes MacAddress, MacAddress8 in the style of IPAddress.  Note I didn't include Printable, as I don't understand how that works.  If someone else wants to add it later, they are welcome to do so.  This is my first time contributing to this repository, so please feel free to point out any mistakes.This library originated on arduino-esp32 (espressif/arduino-esp32#6667).  It was suggested that I contribute to the Arduino core as well :)

Added printTo().  Added index operators and type converters.  See test project here:https://github.com/mrengineer7777/MA_Test.  No further changes expected.