/<CR> - jumps to the currently played song
In case the playlist is big and playback is in "shuffle" mode, it
is relatively hard to quickly find the song, which is actually
played (for instance, to remove this song from playlist).
Added special handling of empty pattern to the "search the
playlist" feature. After search is started ('/' is pressed), user
should not enter any search pattern but just immediately press
<CR> (ENTER). This is interpreted as a command to jump to the
currently played song in the playlist window.