mono-upnp_moved_to_gitlab

Added a GTK client for browsing UPnP devices and servers from
the network. The project uses Mono.Addins to allow new addins which
understand some DCP (such as MediaServer1) to augment the UI with
information pertaining to that DCP. This is an initial commit of
this project and work will continue on it.

This tool also revealed a bug in the core UPnP library which I
fixed (thanks for helping, XBox360).