Copter: Add missing Loiter initialisation lines.

This command is missing to define the desired acceleration that loiter will initalise to.
loiter_nav->clear_pilot_desired_acceleration();

ArduCopter/mode_auto.cpp

@@ -833,6 +833,7 @@ void ModeAuto::land_run()
     // if not armed set throttle to zero and exit immediately
     if (is_disarmed_or_landed()) {
         make_safe_spool_down();
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         return;
     }
@@ -928,6 +929,7 @@ void ModeAuto::loiter_to_alt_run()
     }
 
     if (!loiter_to_alt.loiter_start_done) {
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         _mode = Auto_LoiterToAlt;
         loiter_to_alt.loiter_start_done = true;

ArduCopter/mode_land.cpp

@@ -61,6 +61,7 @@ void ModeLand::gps_run()
     // Land State Machine Determination
     if (is_disarmed_or_landed()) {
         make_safe_spool_down();
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
     } else {
         // set motors to full range

ArduCopter/mode_poshold.cpp

@@ -111,6 +111,7 @@ void ModePosHold::run()
         attitude_control->reset_rate_controller_I_terms();
         attitude_control->set_yaw_target_to_current_heading();
         pos_control->relax_alt_hold_controllers(0.0f);   // forces throttle output to go to zero
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         loiter_nav->update();
 
@@ -133,6 +134,7 @@ void ModePosHold::run()
         target_climb_rate = get_avoidance_adjusted_climbrate(target_climb_rate);
 
         // init and update loiter although pilot is controlling lean angles
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         loiter_nav->update();
 
@@ -147,6 +149,7 @@ void ModePosHold::run()
 
     case AltHold_Landed_Ground_Idle:
 
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         loiter_nav->update();
         attitude_control->reset_rate_controller_I_terms();

ArduCopter/mode_rtl.cpp

@@ -384,6 +384,7 @@ void ModeRTL::land_run(bool disarm_on_land)
     // if not armed set throttle to zero and exit immediately
     if (is_disarmed_or_landed()) {
         make_safe_spool_down();
+        loiter_nav->clear_pilot_desired_acceleration();
         loiter_nav->init_target();
         return;
     }