Setting values are now displayed 10 pixels to the right of setting names, as
passed to MenuSetting::draw.
This commit also contains the following cleanups:
* The height of a row is passed to MenuSetting's draw and touchscreen methods.
* MenuSettingRGBA's magic constant (36) to separate the text for a color's
four components is now a named constant.
* MenuSettingRGBA's color preview squares are now rowHeight - 2 pixels tall,
and have a white border surrounded by a black border to help view the color
it contains in both light and dark themes.
* The rectangle behind the selected setting's name is now drawn by that
setting's drawSelected method.
