FIRST PITCH AND ROLL TUNING

First attempt at tuning pitch and roll at home. Working in horizon
mode. During test flight, the quadcopter yawed to the right (anti-clockwise).

- Pitch and roll first PID tuning complete.

- MAXTHROTTLE reduced to 1500 to prevent too much power being used.

- Magnetometer / Compass still needs improving. It seems to 'lag' behind.

- Fix for compass might be 'Z' signage on Acc or Gyro.