Controller: change yaw and altitude functions
ControlCenter: add yawPID, calibration stuf and output stuff
ControlCenter: comment out PID output limits setting
ITG3200, ADXL345: simplify read functions
Add HMC5883L magnetometer library
Move DEGREES define to utils.h
HMC5883L: make it build
HMC5883L: remove unused variable
utils: add inverted square root
Use different DCM algorithm that uses magnetometer data
DCM: initialize error variables with 0.0
DCM: remove commented out code
Simplifications
Remove quad.h
utils: comment out invSqrt function