CUE support

It would be great to support CUE sheets for image+cue music rips.
There were some patches back in 2009, but the links are long dead.

Forums:

I am attempting to revive one of those patches here: https://github.com/lipnitsk/mocp/tree/cue-sheet. Note that the code does not really work yet: I still need to understand the code and it looks to be missing the CUE parsing logic. Feel free to check out the code though.