Split tutorial in PyGObject and GTK+ 3 parts

[lazka]

I propose splitting the tutorial in two parts:

1. PyGObject documentation, describing the gi API (require_version etc.), GObject, Porting from old static bindings, properties, signals, threading, string handling

2. Gtk+ 3 / Glib documentation, describing the various widgets, how to create your own widget etc., threading, main loop

Because: This would make the tutorial more useful for users of other GI modules like GStreamer/Clutter. It also would make it easier to write new docs for other modules since they can reference the PyGObject parts.

I can provide a patch if this is a welcome change.

[sebp]

As the name suggests, the tutorial is focusing on GTK+, there amount of pygobject-only and glib functions is very small. I don't intend to extend the tutorial to other libraries. I'm not sure what the benefit of the split would be.

[lazka]

It isn't of much benefit if you want to limit it to GTK+. May I ask why you don't want to cover other libraries/pygobject?

[sebp]

I'm not against extending the tutorial per se, it's just that I'd probably won't have the time to extend it. If other people want to contribute. they are more than welcome to, of course. But in the end they could just create their own tutorial and link relevant parts to this tutorial using intersphinx, as you suggested.

[lazka]

Fair enough. If I find time and come up with something useful, I'll might bring it up again.

Thanks for the merge btw.