also polish aspect ratio related code for clarity

The old tooltip description box used GraphicsWidget to provide shared
code to the Graphics config panes for adding descriptions to their
settings.

The description box has been replaced by BalloonTips and serves no
further purpose, so remove it and have the Graphics panes derive from
QWidget instead.

GraphicsInteger is used by the panes in the Graphics config window to
create spin boxes that change their associated config setting, and
update their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigInteger better reflects its
purpose. This should also make it less confusing when ConfigIntegers
are added to other config windows.

GraphicsChoice is used by the panes in the Graphics config window to
create combo boxes that change their associated config setting, and
update their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigChoice better reflects its
purpose. This should also make it less confusing when ConfigChoices are
eventually added to the other config windows.

GraphicsBool is used by the panes in the Graphics config window to
create checkboxes that change their associated config setting, and
update their own state when something else changes the config setting.

Despite its current name nothing about this class is particular to the
Graphics window, so renaming it to ConfigBool better reflects its
purpose. This should also make it less confusing when ConfigBools are
eventually added to the other config windows.