Rework font caching

[KontrollFreek]

Currently, fonts are rendering fine, however if a font uses a different point it is not updated properly. Instead of updating font point every frame based on what is being rendered, re-implement storing the font point with the cache.
In addition, maybe add a way to use a scaled-down version of a font without creating a new one by just scaling down glyph rects when rendering. Texture subsampling should handle scaling fine, however there is the worry of strange integer scaling, so it may not be viable unless it is divisible by two.