Fetch non-numeric track indices from MusicBrainz and Discogs

[mikeacameron]

This is a PR in reference to issue #1831.

[sampsyo]

Great; thanks for getting the ball rolling here!

For the name of the field, maybe alt_track would suffice? Or, alternatively, track_alt to make the relationship with the current track field clear?

Also, to finish things up, would you mind:

• writing a short changelog entry that explains what's going on with that field
• cleaning up the whitespace changes
• taking a look at the tests, which look like they need updating

[sampsyo]

To complete my understanding, what does this number field usually hold? Is it typically a number, but sometimes something else?

[mikeacameron]

My understanding from looking at a handful of XML dumps is that position always holds an integer index of the track and the number holds whatever the user inputted when adding tracks. If you had an album on a double-sided CD, tape, vinyl, etc., then there's the potential of having the number being something like A1, or whatever the case may be.

So it seems to me that simply adding this data should have zero impact with sorting.

[sampsyo]

Cool; that helps! Thanks for elaborating.

[mikeacameron]

I can do what you requested.

I also like the idea of naming it track_alt for consistency.

[mikeacameron]

I believe I got everything done.

[sampsyo]

Looks great; thanks!

I think the problem is related to adding a fixed attribute for the field, which isn't really necessary—I'm going to flip this back to a flexible attribute and see how things go.

[sampsyo]

Looks like that worked! Thanks again for all your work; I'm merging now.