improved the logic in distant chat. Now all traffic is referred to by the GXS id of the contact instead of virtual peer id which would change with tunnel route. Work still needed to fix up the GUI

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@7687 b45a01b8-16f6-495d-af2f-9b41ad6348cc