CloudViewer: fixed opengl not refreshed on update (VTK9). Fixed File Explorer hanging (Qt 5.12). Fixed backup database not deleted after a recovery.

app/src/main.cpp

@@ -50,6 +50,10 @@ int main(int argc, char* argv[])
 	ULogger::setType(ULogger::kTypeConsole);
 	ULogger::setLevel(ULogger::kWarning);
 
+#ifdef WIN32
+	CoInitialize(nullptr);
+#endif
+
 #ifdef RTABMAP_PYTHON
 	PythonInterface python; // Make sure we initialize python in main thread
 #endif