[rotorcraft] fix takeoff-land-takeoff in nav via flightplan

conf/airframes/examples/quadrotor_lisa_m_2_pwm_spektrum.xml

@@ -39,6 +39,8 @@
       <define name="AHRS_GRAVITY_UPDATE_NORM_HEURISTIC" value="TRUE"/>
     </subsystem>
     <subsystem name="ins"/>
+
+    <!--define name="KILL_ON_GROUND_DETECT" value="TRUE"/-->
   </firmware>
 
   <servos driver="Pwm">

conf/flight_plans/rotorcraft_basic.xml

@@ -71,8 +71,12 @@
     </block>
     <block name="flare">
       <exception cond="NavDetectGround()" deroute="Holding point"/>
+      <exception cond="!nav_is_in_flight()" deroute="landed"/>
       <call fun="NavStartDetectGround()"/>
       <stay climb="-0.8" vmode="climb" wp="TD"/>
     </block>
+    <block name="landed">
+      <attitude pitch="0" roll="0" throttle="0" vmode="throttle" until="FALSE"/>
+    </block>
   </blocks>
 </flight_plan>

sw/airborne/firmwares/rotorcraft/navigation.c

@@ -341,4 +341,11 @@ bool_t nav_detect_ground(void) {
   return TRUE;
 }
 
+bool_t nav_is_in_flight(void) {
+  if (autopilot_in_flight)
+    return TRUE;
+  else
+    return FALSE;
+}
+
 void nav_home(void) {}

sw/airborne/firmwares/rotorcraft/navigation.h

@@ -81,6 +81,7 @@ unit_t nav_reset_alt( void ) __attribute__ ((unused));
 void nav_periodic_task(void);
 void nav_move_waypoint(uint8_t wp_id, struct EnuCoor_i * new_pos);
 bool_t nav_detect_ground(void);
+bool_t nav_is_in_flight(void);
 
 void nav_home(void);