Unaligned step

[georgealways]

Corrects cases for number controller where min or max are not divisible by step (#141)

Number controllers will begin incrementing by step, starting from min if it's defined. If min is not defined, it will decrement by step starting from max. If neither are defined, step will behave as before, starting from zero.

After this change, values produced by number controllers are only guaranteed to be divisible by step so long as both min and max are also divisible by step.

Note to self: the change to the way globals work in the test runner shouldn't be part of this PR.