First working OOP based Arduino bot

Had to make mods to the Motor and Plant classes to get control
of both motors.
minor style edits to Plant.h
turned debug commenting off
Plant is an abstract class. Rover_plant inherits from Plant

Another step toward a fully OOP configuration.  This will
allow me to create another plant for functions other than driving
the motors.  Thus I can have an LED light plant that is also
attached to the controller as well as a touchscreen_plant and
any other actuators that the robot will need.
Moved Rover_plant to its own library

I want to keep this library with the base classes.  Derived plants,
sensors and controllers belong in their own libraries.
Updated with namespace State for enums calls to LED plant