Use enums instead of defines
Merge branch 'enums'

Conflicts:
	firmware/examples/PID_AdaptiveTunings/PID_AdaptiveTunings.ino
	firmware/examples/PID_Basic/PID_Basic.ino
	firmware/examples/PID_RelayOutput/PID_RelayOutput.ino
	firmware/pid.cpp
	firmware/pid.h
Revert keywords.txt to match enums
Bump minor version