Remove magic numbers in Cubescript UIs

[no-lex]

The current UI system utilizes many magic constants in its padding and object sizes which should be standardized to modifiable constants. Using proper constants for this behavior should make it possible to clearly standardize UI forms and make uniform UX design simpler.

[b-sharman]

Hi, could you assign this issue to me please?

[no-lex]

Great, you've been assigned.

You'll likely need to tabulate all magic numbers and then figure out what semantics they should have (e.g. button width, height, etc.), before being able to create constant aliases for them.

Additionally, some work setting defaults for elements which are almost always given a particular number might be worth doing (though not necessarily in the scope of this particular issue).