BGE: Fix T46338 replace mesh from an other scene.

To make consistent with KX_GameObject.replaceMesh, we don't allow this behavior but print an error message for the replace mesh actuator.
e.g : Warning: object "Cube" from ReplaceMesh actuator "Edit Object" uses a mesh not owned by an object in scene "scene1"

Reviewers: youle.

source/gameengine/Converter/KX_ConvertActuators.cpp

@@ -505,6 +505,13 @@ void BL_ConvertActuators(const char* maggiename,
 					{
 						RAS_MeshObject *tmpmesh = converter->FindGameMesh(editobact->me);
 
+						if (!tmpmesh) {
+							std::cout << "Warning: object \"" << objectname <<
+							"\" from ReplaceMesh actuator \"" << uniquename <<
+							"\" uses a mesh not owned by an object in scene \"" <<
+							scene->GetName() << "\"." << std::endl;
+						}
+
 						KX_SCA_ReplaceMeshActuator* tmpreplaceact = new KX_SCA_ReplaceMeshActuator(
 						            gameobj,
 						            tmpmesh,