Feature Request: load saved glyph cache texture for use in font

[alex-dot]

I just realised that one couldn't load a prerendered glyph cache texture from file/data and plug it into a loaded font.

Or at least, I don't see how: The only glyph-related public functions in in AbstractFont are fillGlyphCache and createGlyphCache, which both (re-)generate the glyph texture.

Currently, the glyph texture generation takes most of the boot time and caching the font would speed that up quite a lot.