Add a song highlighter

[thegoldknight]

Hi, thanks for creating and maintaining this theme! I think it would be really useful if you could implement a song highlighter that would indicate which song that is selected, since it's really hard to tell what is selected and especially so when highlighting multiple songs.

[Astromations]

Just added it! Thanks for the heads up. Didn't notice the indicator was so subtle.

[thegoldknight]

Awesome, thanks!