oops.
spektrum support was broken, now fixed.

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@238 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61
Added GIMBAL_MIXTILT (16) to gimbal_flags. Setting gimbal_flags=16 will use "mixed" gimbal i.e. SERVO_MIX_TILT from MultiWii. Untested, but should work(tm).

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@239 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61