SDL_ttf isn't really designed to be used with OpenGL. It caches glyph
bitmaps in memory, whereas we want to cache glyph textures on the GPU.
By using FreeType directly we avoid creating and destroying a new
texture every time a glyph is rendered.
Additionally, all glyph textures (including fnl-derived glyphs) now use
the GL_RED internal format instead of GL_RGBA.
Nunuhara Cabbage
2262f7067c