Implementation of the FreeType 2 cache subsystem, which limits the number of concurrently-opened FT_Face and FT_Size objects, as well as caching information like character maps to speed up glyph id lookups. This time with the option of opening FontBLFs that are not cached. See D15686 for more details. Differential Revision: https://developer.blender.org/D15686 Reviewed by Brecht Van Lommel