Improvements to SITL to make paths more flexible. (#5181) (#5255)

* Path cleanup for SITL.

* Restructured sitl scripts dir.

* Set integration tests to use ekf2 for vtol.

* Fix sitl paths for mac.

Tools/setup_gazebo.bash

@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+# Setup environment to make PX4 visible to Gazebo.
+#
+# Note, this is not necessary if using a ROS catkin workspace with the px4
+# package as the paths are exported.
+#
+# License: according to LICENSE.md in the root directory of the PX4 Firmware repository
+
+if [ "$#" != 2 ]
+then
+    echo usage: source setup_gazebo.bash src_dir build_dir
+    echo ""
+    return 1
+fi
+
+SRC_DIR=$1
+BUILD_DIR=$2
+
+# setup Gazebo env and update package path
+export GAZEBO_PLUGIN_PATH=${BUILD_DIR}/build_gazebo:${GAZEBO_PLUGIN_PATH}
+export GAZEBO_MODEL_PATH=${GAZEBO_MODEL_PATH}:${SRC_DIR}/Tools/sitl_gazebo/models
+# Disabling the remote model download seems only necessary with Gazebo 6
+#export GAZEBO_MODEL_DATABASE_URI=""
+export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:${SRC_DIR}/Tools/sitl_gazebo/Build/msgs/:${BUILD_DIR}/build_gazebo
+echo -e "GAZEBO_PLUGIN_PATH $GAZEBO_PLUGIN_PATH"
+echo -e "GAZEBO_MODEL_PATH $GAZEBO_MODEL_PATH"
+echo -e "LD_LIBRARY_PATH $LD_LIBRARY_PATH"