I'll work on making it more generic.
So far it querys faster than kdtree, but building the tree is slower.
And bvhtree NN uses an heuristic based on the last match.
Shrinkwrap (OBCube)24578 over (OBSuzanne)31658
kdtree
build: 30.000000ms
query: 1360.000000ms
bvhtree
build: 140.000000ms
query: 490.000000ms
Shrinkwrap now uses bvhtree (binary tree, 6dop) for nearest vertex.