WIP: General Documentation

[sp1ritCS]

depends on #128

this adds all files required to build the µTeX documentation using Doxygen. It also ships a custom theme, heavily inspired by the theme gi-docgen uses by default (the docs for the GTK widget introduced in my other PR) and somewhat based upon doxygen-awesome. ~~Mobile support is currently very broken tho.~~

the CI publishes documentation as artifacts, if you want to take a look at the current design.

[sp1ritCS]

So, I've implemented support for viewing pages on mobile and I've added a (WIP) page about CLM Fonts.

whats missing now is:

• QT5 Documentation (@PikachuHy I think you are responsible for most of the QT stuff, could you look into that?)
• Win32 Documentation
• Flutter/Skia Documentation?
• Guide to implement new platforms
• Fully specify the CLM file format.

@NanoMichael could you maybe look into writing documentation for Flutter/Skia and the CLM file format (see the table in doc/fontdoc.h), as I don't have much experience with either of them

I don't quite know why, but the version of doxygen that the ubuntu CI ships with is too old and results in a broken search bar / broken nav on mobile. But that issue doesn't occur when building on my machine (doygen 1.9.4).

[NanoMichael]

could you maybe look into writing documentation for Flutter/Skia and the CLM file format (see the table in doc/fontdoc.h), as I don't have much experience with either of them

Sure, I'll fill out the CLM doc.

[PikachuHy]

QT5 Documentation

Of course, my pleasure