Search: loop by track

I don't expect this to be merged.  I haven't tested manually or run the test suite.  So there is a good chance that it breaks functionality.  I figured this was the easiest way to illustrate the performance regression that I am observing.

For me this diff when trying to add the search results for Avicii to now playing reduces the add time from over a minute to under 1 second.

Let me know in my bug report if you can reproduce/agree on this problem, and I will look at getting together a pull request that could be merged.