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 :^)
This currently has exactly one setting: The background colour for card
games. My thinking is, it's better to not have a Settings application
for each individual game we include in the system, since most will only
have a small number of settings, all Settings windows have tabs anyway,
and I don't want to flood the Settings app list unnecessarily.
As for having a single setting for all the card games: it's nice when
things match. :^)
