Function subtractRect

subtractRect(
    rectOuter: Rectangle,
    rectInner: Rectangle,
    vertical?: boolean,
): Rectangle[]
Breaks the outer rect into 1-4 parts based on the inner rect. If the inner rect doesn't intersect then a 0 length array will be returned.

This assumes both valid (bottom > top, right > left) and non zero rects
Parameters
- rectOuter: Rectangle
  The outer rectangle.
- rectInner: Rectangle
  The inner rectangle.
- vertical: boolean = false
  Subtract vertical before horizontal. Default Value false.
Returns Rectangle[]