[Urwid] repo move from svn to hg

[Ian Ward]

I've moved the Urwid source code from the subversion repository that is 
part of the Urwid Trac site to a new Mercurial repository.  I will move 
the Trac site over to the new repo some time soon.  For now the source 
code may be downloaded by running:

   hg clone https://excess.org/hg/urwid

I would not recommend the master branch for mission-critical functions 
at the moment.

I have been working on a number of features that in retrospect should be 
in their own branches: 256-colour support, wsgi web_display, widget code 
cleanup, partial screen display support.  Now that we have a modern 
version control system having lots of branches won't be a problem.

Ian