-Added ramp-down rate instead of instantly setting ramp to zero when throttle is dropped to bottom. This is to allow "warm-restart" if shutdown was unintentional.
-Actual ESC still goes to zero while throttle is dropped to the bottom, only the ramp counter winds down slowly behind the scenes.
Since motors with increasing speed due to yaw input seem to generate more thrust that motors that slow lose thrust, thus net thrust goes up, causing copter to climb.
Values are a guesstimate, proven out by test flying. This could probably become a parameter.
Extended AP_MotorsTri class to take in pointer to rc_tail servo (rc_7) and we use this servo's REV parameter to determine whether to reverse the output to the tail servo or not
1. it's step towards rearchitecting the current code base ahead of a move to RTOS.
2. internally it uses a MatrixTable for the Quad, Octa, OctaQuad, Y6 frames.
3. it implements the missing stability patch for Octa and OctaQuads (still missing for Y6)
Later check-ins will incorporate into the main ArduCopter code.
Andrew Tridgell
Robert Lefebvre
rmackay9
Adam M Rivera