Fix some compilation warnings due to not casting
Skip to the next track when EOS is reached
Add 'playing' triangle at first column in treeview
Ensure we NULL the gst playbin before exiting
Scroll nicely to selected track
Use dist-xz, no gzip
Make visual improvements to status area
Disable focus on interactive header widgets

We don't want users inadvertently being focus-locked to one of the buttons,
or even the volume slider (Imagine.) while navigating media with the
keyboard.