Fix stop after track

Stop after track would cause now playing widget, OSD, and last.fm
scrobbler to change to next track after stopping. This patch prevents
set_current_row() from firing an event which triggers the track change.
More elegant solution to last commit

set_current_row now takes optional parameter "is_stopping" for when auto stop
is enabled.
Formatting
Comment remove
Merge pull request #4305 from TheUbuntuGuy/master

Fix stop after track.  Fixes #3572