Add support for detecting and extracting PS1 SEQ audio

[m35]

SEQ is a "sequenced" audio format, similar in nature to MIDI.

This outstanding post says converting SEQ to MIDI is quite doable. https://www.reddit.com/r/OsamuSato/comments/snzrfu/sato_videogame_soundtracks_reworked_and_exported/

For SEQ files it's actually really easy. In fact SEQ files are almost identical to MIDI files as they both use the same OP codes(!) It's possible to convert between one and the other back'n'forth almost without losing data (the only data you lose is loop pointers and NRPN data, but those can be rebuilt easily).

Related #36

[Meerkov]

VGMTrans is the reference library I use, and already comes with a few game specific hacks.