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 :^)
Previously, all keydown KeyEvents were accepted, causing parent widgets
not to receive them. With the addition of shortcut handling to keydown,
shortcuts were not called when the ImageEditor was focused.
Specializing point_position_to_preferred_cell for the
RectangleSelectTool as it selects a new cells with a rounding
behavior instead of a flooring behavior
