Sources include various lists on the Internet, as well as the current
Wikipedia page at
https://en.wikipedia.org/w/index.php?title=List_of_ID3v1_Genres&oldid=896774343
but most importantly the list as used by taglib at
https://github.com/taglib/taglib/commit/3e60e339a4bc46e2a1a7aea782502480561a8acf#diff-f86455366624350770f41b4940925dde

Further patches to harmonize the spelling have been sent to taglib and
libid3tag. See also https://github.com/taglib/taglib/pull/942/Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>