Fixed overloaded virtual functions with const vs none warning

scene/resources/room.cpp

@@ -31,7 +31,7 @@
 #include "servers/visual_server.h"
 
 
-RID RoomBounds::get_rid() {
+RID RoomBounds::get_rid() const {
 
 	return area;
 }

scene/resources/room.h

@@ -50,7 +50,7 @@ protected:
 
 public:
 
-	virtual RID get_rid();
+	virtual RID get_rid() const;
 
 	void set_bounds( const BSP_Tree& p_bounds );
 	BSP_Tree get_bounds() const;