* use compose for disjoint union
Last mystery in #114. It turns out that the problem is due to
misunderstanding of the bounding box API: Box::Transform is *not* a safe
over-approximation of the bounding box of the manifold after the
transform. In fact it might be smaller than that if the transform is not
axis aligned. The simple fix is to apply the transform first and then
compute the bounding box, this will also make sure that the bounding box
is tight.
* fix batch union
Co-authored-by: Emmett Lalish <elalish@gmail.com>
Emmett Lalish