[Feature] m-TAGS support

[robot3498712]

https://web.archive.org/web/20220518184137/http://m-tags.org/Media_Metadata.html
https://www.foobar2000.org/components/view/foo_tags

Would possibly be a lot of effort to implement (for an at present niche audience), I however see strong benefits enhancing gonic with such meta tagging capabilities.

Suggestion: Gonic would check for existing mtags, and if found prefer it to embedded tags, augment the tag space.

(Happy to help testing if this is considered.)