Loading a font in BLF would search a list of directory presets however these presets were never used. Remove them as all callers pass in full paths. Also rename FontBLF::name to mem_name as it's only needed as an ID for in-memory fonts (to prevent them being loaded multiple times). Non-unique font loading now compares against the filepath or mem_name when loading from files or memory (before both used `name` which was often the filepath, sometimes the full ID-name).