refacto: add RenderingEngine::cleanupMeshCache

This permits to prevent client to own the mesh cache cleanup logic. It's better in RenderingEngine

src/client/client.cpp

@@ -300,12 +300,7 @@ Client::~Client()
 	}
 
 	// cleanup 3d model meshes on client shutdown
-	while (RenderingEngine::get_mesh_cache()->getMeshCount() != 0) {
-		scene::IAnimatedMesh *mesh = RenderingEngine::get_mesh_cache()->getMeshByIndex(0);
-
-		if (mesh)
-			RenderingEngine::get_mesh_cache()->removeMesh(mesh);
-	}
+	m_rendering_engine->cleanupMeshCache();
 
 	delete m_minimap;
 	m_minimap = nullptr;

src/client/renderingengine.cpp

@@ -225,6 +225,15 @@ bool RenderingEngine::print_video_modes()
 	return videomode_list != NULL;
 }
 
+void RenderingEngine::cleanupMeshCache()
+{
+	auto mesh_cache = m_device->getSceneManager()->getMeshCache();
+	while (mesh_cache->getMeshCount() != 0) {
+		if (scene::IAnimatedMesh *mesh = mesh_cache->getMeshByIndex(0))
+			m_rendering_engine->get_mesh_cache()->removeMesh(mesh);
+	}
+}
+
 bool RenderingEngine::setupTopLevelWindow(const std::string &name)
 {
 	// FIXME: It would make more sense for there to be a switch of some

src/client/renderingengine.h

@@ -56,6 +56,7 @@ public:
 	bool setWindowIcon();
 	bool setXorgWindowIconFromPath(const std::string &icon_file);
 	static bool print_video_modes();
+	void cleanupMeshCache();
 
 	static RenderingEngine *get_instance() { return s_singleton; }