Rotate Cube code cleanup:
Simplified a few calculations of this type:
(360.0 / (x * 2.0)) == 180 / x
Declaration and assignment of variables in one line.
Use pre- instead of postfix de- and increments.
Merged if condition checks.
Added and removed newlines and brackets.
Fixed indentation.
Added TODO comments.
Approved by PS Jenkins bot, Sam Spilsbury.