rdp: fix mouse double click
Currently mouse double click is not working; when double clicking, the following events are handled: QEvent::MouseButtonPress QEvent::MouseButtonRelease QEvent::MouseButtonRelease
So, the problem is that the second "MouseButtonPress" is not generated/handled and sent to the remote session. Qt generates a "QEvent::MouseButtonDblClick" for the second mouse button press, so handle it and send it as a normal button press.