resurrecting ghextris

Someone I know in real life is a big fan of ghextris and while updating his computer
we noticed it was gone from Debian since stretch, because it depends on obsolete
libraries. We couldn't find any activity upstream or anywhere else either.

So we decided to work on porting it from the obsolete python2/gtk2/gnome2 tech
stack to a python3/python3-gi/gtk3/cairo stack. If/when we get it completed
(right now it's possible to start a game and watch the prices drop, but keyboard
input, peice preview, the status bar and most of the menus aren't working yet)
I intend to upload it to Debian, I presume it makes sense to keep it under the
games team and as-such I have requested to join the team.

BTW I notice your wiki page on version control systems still refers to alioth.