Upgrade dependency to (Py)GTK 2.12

[Johannes Sasongko]

Tracking bug for modifying our dependency to (py)gtk 2.12.

We have some backward-compatibility code for GTK+ versions earlier than 2.12 (IIRC we depend on 2.10 previously). Debian stable (lenny) is now at 2.12, so we can safely remove these as general code cleanup.

Some quick grep turns up: DEPS, xlgui/__init__, xlgui/osd. Our packaging scripts need changing as well, but I don't know where those are.

P.S. Ideally we'd love to upgrade to 2.16--which will allow us to remove our libsexy and libeggtrayicon optional dependencies--but I'm a bit hesitant, considering the Debian situation.

[Johannes Sasongko (sjohannes)]

I've made the necessary changes to DEPS and xlgui/__init__. The stuff in xlgui/osd apparently can't be modified because we want a different behaviour to what GTK+ 2.12 provides, so I've only updated the comments to mention this.

I'll ignore packaging scripts for now.