Copter: g.rc_3.control_in range 0 to 1000

Previously the range was throttle_min (normally 130) to 1000 but we can remove this awkward range and use 0 to 1000 now that the attitude controller and motor library inputs are in the 0 to 1 range.

ArduCopter/radio.cpp

@@ -32,7 +32,7 @@ void Copter::init_rc_in()
     channel_roll->set_angle(ROLL_PITCH_INPUT_MAX);
     channel_pitch->set_angle(ROLL_PITCH_INPUT_MAX);
     channel_yaw->set_angle(4500);
-    channel_throttle->set_range(g.throttle_min, THR_MAX);
+    channel_throttle->set_range(0, THR_MAX);
 
     channel_roll->set_type(RC_CHANNEL_TYPE_ANGLE_RAW);
     channel_pitch->set_type(RC_CHANNEL_TYPE_ANGLE_RAW);