[Communication] Dropping MP3

[spessasus]

As I and @Cacodemon345 agreed in #117, SFe should not support MP3. Here's why:

• obsolete: opus does everything MP3 can, but better. What's the point of MP3?
• proprietary formats are not cool.
• saga mentioned Frankenstein mp3s and some decoder limitations requiring additional libraries. this points to the fact that MP3 can be very messy and Vorbis solves everything. I don't know the codecs all that well, but I think that they are right.
• I do not want another bulky decoder doubling the size of my website and npm package. I'd also have to find one that's compatible with MIT.

So the new supported format list should be:

• Vorbis
• Opus
• FLAC
• WAV (uncompressed, or as a wav container as I proposed in [Feature enhancement] Allow WAV as SF3 "compression" #102)

That should be enough. Uncompressed, lossless, two widely supported lossy formats.

[sylvia-leaf]

This has been solved in update 6. Support for wav in container is shown using these flags:

• 03:00 bit 1 set
• 03:01 bits 1-3 clear

This says "sfSampleType bit 4 is in use, but no compression formats are used."