Tri: _min_throttle interpreted as 0~1000 range for throttle_lower flag

limit.throttle_lower flag becomes true when the throttle passed into the
motors lib (which is in the 0 ~ 1000 range) is below _min throttle.
This makes the interpretation of the THR_MIN parameter consistent
between the main code (which uses 0 ~ 1000 range) and the motors lib
(which previously used the RC3_MIN ~ RC3_MAX range).
The remaining problem however is that the output of the motors continues
to use THR_MIN as if it were a pwm.  I don't believe this is a dangerous
problem however.
MotorsMatrix: _min_throttle interpreted as 0 ~ 1000 range for throttle_lower flag

Also trigger throttle_upper flag when throttle in reaches 1000
Copter: ReleaseNotes for AC3.2-rc11
Copter: version to AC3.2-rc11
VRBRAIN: modified target clean
DataFlash: Added four more channels for logging
AP_Compass: VRBRAIN. Deal with external mag connected on internal I2C on VRBRAIN 4.5
This enables user to set the external parameter to true even if only one compass is connected
VRBRAIN: defined AirSpeed inputs for ArduPlane on VR Micro Brain 5
VRBRAIN: added flag for to build versions with different kind of RC Inputs
VRBRAIN: added new board VR Brain 5 PRO
VRBRAIN: added script for build all VirtualRobotix binaries