Finally: Bidi, shaping and line wrapping

It turned out to be more tricky than I imagined, but now it works: a simple, but full text layout engine, that supports bidirectional text with full shaping (where needed) and is capable of wrapping bidirectional text correctly. The code is probably horrible and very inefficient, though.

In the bottom you can see the reference rendering (rendered by a GTK app, i.e. Pango), in the top is my rendering. Note that I have no idea what the Arabic text actually means, I don't know any Arabic language.  I can read the script a bit, but that's all. The text was copy & pasted together from somewhere.

Now it's time to start digging into libass, cleaning up some of the mess and preparing it for inclusion of this functionality.