Add keyboard shortcuts (i.e. Ctrl-A to Select All)

Also, don't reset after each function. After I download the album cover I may want to download the lyrics or the artist photo. In its current state I have to reselect everything.

One other suggestion: Maybe I missed it but I didn't see a group download function that would download all our selected information. It'd be nice to have something that allowed us to choose what we wanted, then let it get this information for all the artists/songs in the database while we did something else.