-added 8 hardware PWM's for servos on MEGA boards. Servo outputs are 44,45,46,11,12,6,7,8
-added gimbal servo stretcher usable with HW PWM's. We can get 180 degrees servo move without servo modification.

git-svn-id: http://multiwii.googlecode.com/svn/trunk/MultiWii_shared@1384 02679b44-d973-9852-f2fa-63770883b36c