Better feedback while searching, and more

Changes

- Shows progress bar while searching and No Results of none.
- Updates next and previous song more quickly.
- Fixed bug where skipping songs while app not active causing old song
to be displayed on now playing when navigated back to.
- Up Next properly displays the actual next song when the end of the
playlist is reached and it prepares to loop.
- Pressing previous at the start of a playlist sends you to the last
song.
- If you press previous after the first 7 seconds of a song, it just
sends you to the beginning.
- System tray has same theme as app and fixed splash screen color