Introduce tag alias

[youstanzr]

We can add alias tags in the setting (once #57 done) where it there would be alias and primary text field and add button that adds to a small table view. The primary is always whats shown in the filter picker but aliases of the primary is picked up when filtering for primary. Aliases should not appear in the filter picker view.

This is extremely helpful in cases that someone add a tag called 'oldies' for example and in another song, the user adds a tag called 'classics'. In this example, it would be easy to make 'classics' an alias of 'oldies' and everything would work nicely.

[paulofaria]

Can you please check why the test are failing and fix the issues so I can merge?

[nerdsupremacist]

Oh that's weird. It failed checking out NIO (timeout). Perhaps retriggering it would help

[nerdsupremacist]

Well that fixed it!

[paulofaria]

Hello, @nerdsupremacist. I'm closing this PR because it is doing much more then what is in the title. I believe this happened because you based your PR from your master branch. This caused all of the other changes to appear here as well. I started trying to resolve the conflicts, but since you based this PR off of master, I would be committing to your master branch and that wouldn't be cool. Feel free to create another PR based on a separate branch. Thank you!