support launching gazebo automatically for SITL

Makefile

@@ -138,7 +138,7 @@ run_sitl_quad: posix
 	Tools/sitl_run.sh posix-configs/SITL/init/rcS none jmavsim
 
 run_sitl_iris: posix
-	Tools/sitl_run.sh posix-configs/SITL/init/rcS_iris_gazebo
+	Tools/sitl_run.sh posix-configs/SITL/init/rcS_iris_gazebo none gazebo
 
 run_sitl_plane: posix
 	Tools/sitl_run.sh posix-configs/SITL/init/rc.fixed_wing

Tools/sitl_run.sh

@@ -7,6 +7,15 @@ then
 	ant
 	java -Djava.ext.dirs= -cp lib/*:out/production/jmavsim.jar me.drton.jmavsim.Simulator -udp 127.0.0.1:14560 &
 	cd ../..
+elif [ "$3" == "gazebo" ]
+then
+	if [ -x "$(command -v gazebo)" ]
+	then
+		gazebo ${SITL_GAZEBO_PATH}/worlds/iris.world &
+	else
+		echo "You need to have gazebo simulator installed!"
+		exit 1
+	fi
 fi
 cd build_posix_sitl_simple/src/firmware/posix
 mkdir -p rootfs/fs/microsd