Clean up Rect set operations (union, intersect, diff, overlaps)

[ffreyer]

This adds bbox_diff(a, b) which calculates the bounding box of all rects produced by cutting b out of a (without calculating those rects).

This is something I will probably need for optimizing an SDF volume plots in Makie. Doesn't need to be merged/tagged until I get that near completion

[ffreyer]

https://en.wikipedia.org/wiki/Allen%27s_interval_algebra

GeometryBasics.jl/src/primitives/rectangles.jl

Lines 441 to 486 in 9918b18

	# http://en.wikipedia.org/wiki/Allen%27s_interval_algebra
	function before(b1::Rect{N}, b2::Rect{N}) where {N}
	for i in 1:N
	maximum(b1)[i] < minimum(b2)[i] || return false
	end
	return true
	end
	meets(b1::Rect{N}, b2::Rect{N}) where {N} = maximum(b1) == minimum(b2)
	function overlaps(b1::Rect{N}, b2::Rect{N}) where {N}
	for i in 1:N
	maximum(b2)[i] > maximum(b1)[i] > minimum(b2)[i] &&
	minimum(b1)[i] < minimum(b2)[i] || return false
	end
	return true
	end
	function starts(b1::Rect{N}, b2::Rect{N}) where {N}
	return if minimum(b1) == minimum(b2)
	for i in 1:N
	maximum(b1)[i] < maximum(b2)[i] || return false
	end
	return true
	else
	return false
	end
	end
	function during(b1::Rect{N}, b2::Rect{N}) where {N}
	for i in 1:N
	maximum(b1)[i] < maximum(b2)[i] && minimum(b1)[i] > minimum(b2)[i] || return false
	end
	return true
	end
	function finishes(b1::Rect{N}, b2::Rect{N}) where {N}
	return if maximum(b1) == maximum(b2)
	for i in 1:N
	minimum(b1)[i] > minimum(b2)[i] || return false
	end
	return true
	else
	return false
	end
	end

This stuff makes sense for intervals but I fail to see how this should generalize to rectangles. For examples saying one interval is before another is clear, but for 2D rects it could mean being outside towards -x, or -y or -(x, y) (current), or any of those. meets(a, b) could be:

--.--
a | b
--'--

or

| b |
|---|
| a |

or (current)

  | b
--+---
a |

or other rotations. Also, for the edge versions, do widths need to match for the dimension that doesn't meet?

This doesn't seem clear enough to have. It's been there since the dawn of GeometryTypes 11 years ago