import behaviour assumes perfect mb recording match (particularly bad for acoustid submissions)

So, I did something rather silly the other day. I'd imported a fair amount of music using beets, and used the `chroma` plugin to submit the fingerprints to acoustid.

It then only today hit me that I hadn't carefully checked that the matches were for the correct releases/mediums.

**That means that I most likely made a number of erroneous submissions.**

The fact that the default behaviour is to not be timid when importing combined with the fact that users might not realise the importance of only submitting fingerprints when you are sure you have matched the audio files to precisely the correct musicbrainz release seems like a recipe for bad data.

One simple improvement would be to add some kind of warning when doing a submission. This warning should probably also be added to the documentation.

**_On a related more general note..**_

I was having a think about what the optimum workflow might be for ensuring that you only submit fingerprints for things in your library for which you have a high confidence of the metadata being accurate, and the musicbrainz release id being correct. (This doesn't actually just apply to acoustid submissions, it applies more generally to keeping track of which parts of your library are rougher than others)

Some imported music may have unclear provenance, but you still want to improve its tags based on a "good enough" match. The way things stand, the tags will be updated with musicbrainz metadata pointing to a specific release, and there is no way to distinguish between those vague matches in your collection, and the things that you have carefully ensured to be perfect matches.

One solution could be to allow making a distinction at the point of importing. An "Apply this and mark with high confidence" action maybe. Or maybe even "Apply only non release specific tags", which wouldn't add musicbrainz IDs at all.

You could then do a `beet submit confidence:high` (or if going the route of only adding non release specific tags when uncertain, just `beet submit`), and avoid sending dodgy data.

Sorry if this is a bit of a stream of consciousness :)