Added song progress resume

Converted this morning's coffee into a nice new feature:

Song progress resuming. Performs the standard check, and if its to
resume a song, it doesn't just blindly start the song from the
beginning, it now plays the song from its last known song position,
which theoretically will be within 5-10 seconds of where I last heard
it.
Bugfixes

Removed database key thing because it doesn't work anymore. Not sure
why.

Fixed a typo.

Changed the smartshuffle randomplay method, as the original one would
cut the last 10 seconds of the song off.

Also fixed another concurrency issue at some point. Not sure when. Or
how. But it works now. Hurrah.
Merge pull request #2 from NovaXeros/dev

Dev