GCS_MAVLink: Added definition for MAV_CMD_NAV_LOITER_TO_ALT

libraries/GCS_MAVLink/message_definitions/common.xml

@@ -610,6 +610,16 @@
                     <param index="6">Empty</param>
                     <param index="7">Desired altitude in meters</param>
                 </entry>
+                <entry value="31" name="MAV_CMD_NAV_LOITER_TO_ALT">
+                    <description>Begin loiter at the specified Latitude and Longitude.  If Lat=Lon=0, then loiter at the current position.  Don't consider the navigation command complete (don't leave loiter) until the altitude has been reached.  Additionally, if the Heading Required parameter is non-zero the  aircraft will not leave the loiter until heading toward the next waypoint. </description>
+                    <param index="1">Heading Required (0 = False)</param>
+                    <param index="2">Radius in meters. If positive loiter clockwise, negative counter-clockwise, 0 means no change to standard loiter.</param>
+                    <param index="3">Empty</param>
+                    <param index="4">Empty</param>
+                    <param index="5">Latitude</param>
+                    <param index="6">Longitude</param>
+                    <param index="7">Altitude</param>
+               </entry>
                <entry value="80" name="MAV_CMD_NAV_ROI">
                     <description>Sets the region of interest (ROI) for a sensor set or the vehicle itself. This can then be used by the vehicles control system to control the vehicle attitude and the attitude of various sensors such as cameras.</description>
                     <param index="1">Region of intereset mode. (see MAV_ROI enum)</param>