m4a: support multi-track files as well
removed unused label
vorbis: skip trying to read tags when there is none
add opus support
update copyright years
Revert "try another license"
don't ignore valid audio files without tags
id3v2: make mp3 format check better
update readme
try another license
extension shouldn't matter, remove this logic and add Funknown
optional TOC handler
id3v2: add a note for possibly reading TOC in the future
id3v2: don't stop at false frame sync
readme: forgot the -I.
move stuff around and clean up
change callback api to include raw "key" of the tag, add Tunknown type. this allows programs to read ALL text tags