Copter: allow passthru for ch 9 ~ 14

Based on work by Emile Castelnuovo
Plane: disable the CLI if AFS failsafe enabled on APM2

the flash space is a bit too low for both CLI and AFS
APM_OBC: added heartbeat() method

this is used for when the plane is calibrating sensors, to ensure
heartbeat is continued to the failsafe board
Plane: send heartbeat to AFS when calibrating sensors
Copter: update AC3.2-rc10 release notes