The callback checks if 2 nodes intersect (not just their AABB).
Advantages:
- theres no need to allocate overlaps which are later ignored.
- expensive intersection tests will run multi-threaded.
Currently only used for Python API.
Originally D966 by @lukastoenne, with own additions
- trees can be initialized from Object's, BMesh,
or passed in as vert+polygon arrays.
- original indices of ngons/faces are used. (instead of tessellated indices).
- ray_cast, find_nearest methods
- find overlapping faces between 2 trees
