allow controlling external XOR gate connected to PB2 (BOOT1) to invert USART2_RX signal on F1. Currently used by sbus driver.
On second thought, no need to make inverter configurable. only sbus will use it, and the driver can set inversion automatically.
Fixing gimbal_flags not working when feature SERVO_TILT was enabled. This was done by properly calculating servo offset instead of depending on enabled features/mixers.
remove unnecessary variable
unroll loop for better code size

gcc remove 29 bytes here
Merge pull request #122 from treymarc/patch-7

remove unnecessary variable
Merge pull request #123 from treymarc/patch-9

unroll loop for better code size
Merge remote-tracking branch 'multiwii/master'