ADXL, HMC, and ITG Custom Libraries/Classes

Rewrote basic 3 sensor code to use libraries and classes instead. Also
eliminates unnecessary code in stock libraries. Total memory savings are
around 1.5 kb. Needs to be added to QC6. Also, all sensor readings seem
to remain stable. Barometer readings often start at infinity for some
reason upon major code uploads. Needs checked.