Glade branched for gnome 2.18

[Tristan Van Berkom <tvb gnome org>]

As development for gnome 2.18 has frozen solid, we're obviously going
to have to branch out. so I did that.

translators, release-team and doc writers should know that the
2.18 branch can be found in the standard location:
  "svn.gnome.org/svn/glade3/branches/gnome-2-18"

I've already requested a string break for some important blockers
(i.e. glade in 2.18 is feature incomplete without them)... and I'll
be periodically requesting code freeze breaks for minor bug fixes
on Glade 3.2.x (for instance I have a simple fix pending on:
http://bugzilla.gnome.org/show_bug.cgi?id=396436 ).

For those working on Glade, development will continue in 'trunk'
and instead of how we worked for 3.0/3.1, we'll be committing
bugfixes right onto trunk and porting them back into 'gnome-2-18'
periodically upon approval from the release-team (we'll try to
keep track of important bugfixes pending approval in the TODO
file or something).

There's a final release this week for 2.18, hopefully we'll
get that string break in there by that time, and we'll be
releasing that from the branch, the branch will at that
point become 3.2.x, and I'll bump 'trunk' to be 3.3.x at
that time.

Alright I think thats it for now... I'll write up something
more formal wrt bug 396436 once I get this show on the road.

Cheers,
                      -Tristan