Create the BattleSetting class

For now, we have the class docstring with documentation on class constants
and instance attributes, as well as declaration and assignment for the
class constants.
UML: More changes to Option and BattleSetting

These edits include:
* Swapping the values for the text color constants (obviously, the
  lighter color should be the highlight color).
* Adding two integer arguments to BattleSetting's init() method for
  the x and y-coordinates. (Note how the same thing was forgotten
  in the Option class until one of the previous commits!)
* Allowing BattleSetting to polymorph the highlight() and unhighlight()
  methods, since it will also need to recolor the separate value text.
Add the transform() method to Graphics module

You never know when this might come in handy.
Create init() method for BattleSetting