Improvements to remix credit automation

[ligeia]

i'm wondering if you'd be interested in a PR for some work I did to extend your MB remix credit automation script.

I linked together the done/add button across rows. When you mark track 1's remixer credit as Done, it pops up the add credit for track 2 automatically and so on until you've done all those. The same functionality applies to the "remix of" and "edit of" relationships: start at the top and it will walk down the column for you, making it faster to set those relationships.

I also added some new logic for tracks which are likely to be remixed by two artists. This will add, for example, two remixer credits for you and walk you through those before taking you to the next track.

I also found that including the original artist's name in the Recording search for "remix of" and "edit of" credits makes it much faster to find results for commonly used words. "Heaven", for example, will return an awful lot of tracks but appending an artist in there makes you much more likely to quickly find the recording you're looking for.

If some or all of that is interesting to you, I'll start working on a PR.