Plane: use a common reset for uniform landing wipe

ArduPlane/ArduPlane.cpp

@@ -569,8 +569,6 @@ void Plane::handle_auto_mode(void)
         if (nav_cmd_id != MAV_CMD_NAV_CONTINUE_AND_CHANGE_ALT) {
             steer_state.hold_course_cd = -1;
         }
-        landing.complete = false;
-        landing.pre_flare = false;
         calc_nav_roll();
         calc_nav_pitch();
         calc_throttle();

ArduPlane/altitude.cpp

@@ -657,7 +657,7 @@ void Plane::rangefinder_height_update(void)
         if (now - rangefinder_state.last_correction_time_ms > 5000) {
             rangefinder_state.correction = correction;
             rangefinder_state.initial_correction = correction;
-            landing.initial_slope = landing.slope;
+            landing.set_initial_slope();
             rangefinder_state.last_correction_time_ms = now;
         } else {
             rangefinder_state.correction = 0.8f*rangefinder_state.correction + 0.2f*correction;

ArduPlane/commands_logic.cpp

@@ -13,10 +13,11 @@ bool Plane::start_command(const AP_Mission::Mission_Command& cmd)
         DataFlash.Log_Write_Mission_Cmd(mission, cmd);
     }
 
+    landing.reset();
+
     // special handling for nav vs non-nav commands
     if (AP_Mission::is_nav_cmd(cmd)) {
         // set land_complete to false to stop us zeroing the throttle
-        landing.init_start_nav_cmd();
         auto_state.sink_rate = 0;
 
         // set takeoff_complete to true so we don't add extra elevator
@@ -137,8 +138,7 @@ bool Plane::start_command(const AP_Mission::Mission_Command& cmd)
         break;
 
     case MAV_CMD_DO_LAND_START:
-        //ensure go around hasn't been set
-        landing.commanded_go_around = false;
+        // handled in landing.reset()
         break;
 
     case MAV_CMD_DO_FENCE_ENABLE:
@@ -382,7 +382,6 @@ void Plane::do_nav_wp(const AP_Mission::Mission_Command& cmd)
 
 void Plane::do_land(const AP_Mission::Mission_Command& cmd)
 {
-    landing.commanded_go_around = false;
     set_next_WP(cmd.content.location);
 
     // configure abort altitude and pitch
@@ -398,8 +397,6 @@ void Plane::do_land(const AP_Mission::Mission_Command& cmd)
         auto_state.takeoff_pitch_cd = 1000;
     }
 
-    landing.slope = 0;
-
     // zero rangefinder state, start to accumulate good samples now
     memset(&rangefinder_state, 0, sizeof(rangefinder_state));
 }

ArduPlane/system.cpp

@@ -337,11 +337,8 @@ void Plane::set_mode(enum FlightMode mode, mode_reason_t reason)
     // reset landing check
     auto_state.checked_for_autoland = false;
 
-    // reset go around command
-    landing.commanded_go_around = false;
-
-    // not in pre-flare
-    landing.pre_flare = false;
+    // reset landing
+    landing.reset();
     
     // zero locked course
     steer_state.locked_course_err = 0;