GameViewSettings slightly incorrect defaults

[PennyJim]

GameViewSettings.default_show_value very specifically says it is the default for all other values. Yet all other values say `true` is their default. They should probably be changed to "Value of `default_show_value`" just like SpriteSheet.line_length with the default setting having an actual default.

I wouldn't blame you if you want to instead do something along the lines of "Value of `default_show_value` or `true` if unset" for clarity sake, but then I'd recommend you do that for any other instance of "Value of" for consistency.