Added feedforward ability and windup control.

In addition to feedforward with gain and offset, also added
control over windup.
Also cleaned up some variable names for consistent capitalization.
Updated with info for additional contributor.
Moved feedforward computation out of library.

Modified as per Brett's suggestion to externalize calculation
of the feedforward term. A pointer is passed in to the
overloaded constructor.
Cleaned up windup limits.
Update README.txt
changed version number to avoid conflict with original project
Merge remote-tracking branch 'origin/master'

Conflicts:
	PID_v1/PID_v1.cpp
	PID_v1/PID_v1.h
	README.txt