Refactor of updatePID, still needs testing
converted p i and d to fixed7_9 instead of fixed23_9.
added constrainTemp funciton instead of constrain macro from Arduino.h
Added post build event to output function sizes using avr-nm
Merge branch 'feature/dynaconfig' of https://github.com/BrewPi/brewpi-avr into feature/dynaconfig
made isDeviceValid output debug level 2