Migrate to python-gi about labyrinth HOT 2 OPEN

My first attempt at porting got stuck on some parts of pango that aren't yet exposed through the bindings - specifically, the means to create and combine Pango 'attributes', which represent a font style option (such as bold) together with the span of text to which it should be applied.

This code in Pitivi works around something similar, and I exchanged emails with the author of that bit, Matas Brazdeikis. But I couldn't get it working within Labyrinth.

Potential ways out:

• Pango can expose the necessary bits to introspection in future versions (see e.g. this bug)
• Matas may be able to look more closely at our code at some point.
• There may be another way of coding without directly controlling pango. But even if there is, I've no idea what it might be.

from labyrinth.

The GObject introspection interface to Pango has improved somewhat, and I was able to get a bit further. I also started making it Python 3 compatible, because that was easier than getting the bindings set up on Python 2 again.

However, I'm stuck - for now - on another limitation of the Pango introspection API: https://gitlab.gnome.org/GNOME/pango/-/issues/476 . Specifically, it fails on a line like this:

from labyrinth.