Copter: rename roi_WP to just roi

A Vector3f is not a waypoint.

This should really be "Point Of Interest" rather than "Region Of
Interest"

ArduCopter/Attitude.cpp

@@ -33,13 +33,13 @@ float Copter::get_pilot_desired_yaw_rate(int16_t stick_angle)
  * yaw controllers
  *************************************************************/
 
-// roi_yaw - returns heading towards location held in roi_WP
+// roi_yaw - returns heading towards location held in roi
 float Copter::Mode::AutoYaw::roi_yaw()
 {
     roi_yaw_counter++;
     if (roi_yaw_counter >= 4) {
         roi_yaw_counter = 0;
-        _roi_yaw = get_bearing_cd(copter.inertial_nav.get_position(), roi_WP);
+        _roi_yaw = get_bearing_cd(copter.inertial_nav.get_position(), roi);
     }
 
     return _roi_yaw;

ArduCopter/defines.h

@@ -14,7 +14,7 @@
 enum autopilot_yaw_mode {
     AUTO_YAW_HOLD =             0,  // pilot controls the heading
     AUTO_YAW_LOOK_AT_NEXT_WP =  1,  // point towards next waypoint (no pilot input accepted)
-    AUTO_YAW_ROI =              2,  // point towards a location held in roi_WP (no pilot input accepted)
+    AUTO_YAW_ROI =              2,  // point towards a location held in roi (no pilot input accepted)
     AUTO_YAW_FIXED =            3,  // point towards a particular angle (no pilot input accepted)
     AUTO_YAW_LOOK_AHEAD =       4,  // point in the direction the copter is moving
     AUTO_YAW_RESETTOARMEDYAW =  5,  // point towards heading at time motors were armed

ArduCopter/mode.h

@@ -48,7 +48,7 @@ public:
         uint8_t _mode = AUTO_YAW_LOOK_AT_NEXT_WP;
 
         // Yaw will point at this location if mode is set to AUTO_YAW_ROI
-        Vector3f roi_WP;
+        Vector3f roi;
 
         // bearing from current location to the ROI
         float _roi_yaw;

ArduCopter/mode_auto.cpp

@@ -1989,7 +1989,7 @@ void Copter::Mode::AutoYaw::set_roi(const Location &roi_location)
 #if MOUNT == ENABLED
         // check if mount type requires us to rotate the quad
         if(!copter.camera_mount.has_pan_control()) {
-            roi_WP = copter.pv_location_to_vector(roi_location);
+            roi = copter.pv_location_to_vector(roi_location);
             auto_yaw.set_mode(AUTO_YAW_ROI);
         }
         // send the command to the camera mount
@@ -2003,7 +2003,7 @@ void Copter::Mode::AutoYaw::set_roi(const Location &roi_location)
         //      4: point at a target given a target id (can't be implemented)
 #else
         // if we have no camera mount aim the quad at the location
-        roi_WP = pv_location_to_vector(roi_location);
+        roi = pv_location_to_vector(roi_location);
         auto_yaw.set_mode(AUTO_YAW_ROI);
 #endif  // MOUNT == ENABLED
     }
@@ -2022,7 +2022,7 @@ float Copter::Mode::AutoYaw::yaw()
     switch(_mode) {
 
     case AUTO_YAW_ROI:
-        // point towards a location held in roi_WP
+        // point towards a location held in roi
         return roi_yaw();
 
     case AUTO_YAW_FIXED: