gtk-2-24-win32 branch update

[Alexander Larsson <alexl redhat com>]

The gtk-2-24-win32 branch is now in a pretty good state. I fixed a lot
of bugs from bugzilla and stuff from dieters testing
(https://live.gnome.org/GTK%2B/Win32/test-gtk-2-24-win32). I think this
is in a state where we might want to merge it into master. I fixed most
core issues, although I didn't fix the MS-Windows misrendering bugs that
dieter pointed out.

So, could everyone interested in the windows support test this please.
I'd like to make a 2.24 release with this stuff in it so that we have a
final Gtk2 with good win32 support. Obviously we don't want to have any
bad regressions for existing Gtk win32 apps in this release, so *please*
test stuff.

My plan going forward is to mostly leave this code as-is (i.e. mostly
working but no new features) and move towards fixing Gtk 3.x on win32.