Fix or drop ID3v2.2 support

[randoragon]

The spec is only available through the Wayback Machine, it seems: https://web.archive.org/web/20150214031143/http://id3.org/id3v2-00.

This is a tricky topic that I don't have a clear plan or direction for yet. For instance, should I add corresponding 3-letter options for ID3v2.2 frames? i.e. --TT2 instead of --TIT2, etc. This seems like a bit of a pointless endeavor, but I honestly don't know yet. Something to think about.

[randoragon]

I've decided to add support for ID3v2.2. I have no use for it now, but since the id3 crate supports it, I want rsid3 to support it too. How smoothly this will go remains to be seen.