This change the logic to query the tree for nearest neighbors.
Start with a simple sequential query for each point.

This change the logic to query the tree for nearest neighbors.
Start with a simple sequential query for each point.

This move the Node informations to dedicated datastructure
decoupling the actor hierarchy from the data allowing using
adapted pattern for both constructing and querying the tree.

This has been extracted from:
https://lab.nexedi.com/jjerphan/cython_plus_experiments/tree/queue-dispatch/kdtree

The runtime was written by Xavier T. and adapted by Julien J.

The experimentation KDTree was written by Julien J.
Co-authored-by: Xavier Thompson <xavier.thompson@nexedi.com>