This makes Piano exactly as usable as when I started the large refactor
some years ago, which *sounds* like I'm a terrible person but now it (1)
looks nicer and (2) has a flexible backend that can already deal with
aribtrary kinds of processors on any track.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Adds the ability to add a track and cycle through the
tracks from player widget. Also displays the current track
being played or edited in a dropdown that allows
for quick track selection.
