rtabmap: updated list_labels service to return also node ids, added get_plan_nodes service to get path AND node ids

srv/GetPlan.srv

@@ -0,0 +1,11 @@
+# Get a plan from the current position to the goal node or pose 
+
+# The final node of the goal (set 0 to use pose instead)
+int32 goal_node
+# The final pose of the goal position (used only if goalNodeId=0)
+geometry_msgs/PoseStamped goal
+
+# How many meters from the map's graph we can plan (0=infinite)
+float32 tolerance
+---
+rtabmap_ros/Path plan

srv/ListLabels.srv

@@ -1,4 +1,5 @@
 #request
 ---
 #response 
+int32[] ids
 string[] labels