* Implement support for more RDP 5.X features:

  * Sound

  * Serial port redirection

  * Drive redirection


* Keymapping: Support non-dead versions of some dead keys, like
 "acute". It seems like RDP4 only supports the dead versions, but the
  non-dead ones can be simulated by sending a space after the dead
  key. 


* Keymapping: Autodetect which keymap to use.