VS-1680: Arrows Outward [F3 (<-- -->)]

Tags: vs-1680
<--- ---> is assigned to the [F3] function key whenever the Playlist is
displayed.

[F3 (<--- --->)]: This enlarges (in four stages) the display of the Playlist
in the time area. When the waveform is displayed, this enlarges the display of
the waveform in the time area.