Plane: allow changing Q_TRIM_PITCH in flight

change float comparison to is_equal

ArduPlane/quadplane.cpp

@@ -491,7 +491,7 @@ bool QuadPlane::setup(void)
 
     enum AP_Motors::motor_frame_class motor_class;
     enum Rotation rotation = ROTATION_NONE;
-        
+
     /*
       cope with upgrade from old AP_Motors values for frame_class
      */
@@ -1458,7 +1458,12 @@ void QuadPlane::update(void)
     if (!setup()) {
         return;
     }
-    
+
+    if ((ahrs_view != NULL) && !is_equal(_last_ahrs_trim_pitch, ahrs_trim_pitch.get())) {
+        _last_ahrs_trim_pitch = ahrs_trim_pitch.get();
+        ahrs_view->set_pitch_trim(_last_ahrs_trim_pitch);
+    }
+
     if (plane.afs.should_crash_vehicle()) {
         motors->set_desired_spool_state(AP_Motors::DESIRED_SHUT_DOWN);
         motors->output();

ArduPlane/quadplane.h

@@ -241,6 +241,7 @@ private:
 
     // Quadplane trim, degrees
     AP_Float ahrs_trim_pitch;
+    float _last_ahrs_trim_pitch;
 
     // fw landing approach radius
     AP_Float fw_land_approach_radius;