the rewrite of the retroshare core networking stack.
This check-in commits the changes to the TCPonUCP code.
This library has been significantly modified to support
multiple UDP "connections" from a single port.
This requires some trickery and a listener thread.
Code to "STUN" peers was also added.
git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@305 b45a01b8-16f6-495d-af2f-9b41ad6348cc
