New ValueFormatter

I created a simplified value formatter class, which is an abstract class rather
than an interface.

The switch was chosen because the new format has all the methods predefined
(something an interface wouldn't allow) meaning you can extend it and only
change what you want. This also means that you only need one value formatting
class for labels rather than two different classes, it just makes more sense.

Please check the method signatures to learn how to use them, I'm sure you'll
find this new format is much more customizable and faster to use.

I've made the class abstract even though there are no abstract methods or
fields, this is because it would certainly be a mistake to create a
ValueFormatter and not override any methods.

To convert existing code, just use 'extends' instead of 'implements' and change
the names to 'ValueFormatter'. You'll need to change the methods you overwrite
as well, just check the class and use the one you need.