Add "font setup" pane

[pferreir]

The default fonts that come with Indico do not support all possible character sets. Latin-based alphabets are pretty much covered but Asian graphemes are poorly covered.

There are at least two possible solutions for this issue:

• Distribute Indico along with fonts that cover a wider range of the Unicode space;
• Allow people to set custom fonts in the administration area;

Given that we've so far failed to find a font that managed to comply with the first option whilst having an open source-friendly license, maybe the second option would be the simplest. We could delegate on each admin the responsibility of making sure that fonts can be used for the purpose in question and let him/her "upload" the font files to Indico.

There could be font "types": "serif", "sans serif", "monospace" etc... and default fonts for those. Admins would then be able to override the fonts that get used for such font types. Obviously, this would imply replacing the calls for specific fonts in the PDF code with something more general.