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).
d770fd5ac4