Compress list 3 with eliminate_empty_output_lists

See merge request !39

Allow geometry features finer than machine epsilon (#23 on Gitlab)

See merge request !42

Improve max-level error message (Closes #22)

Closes #22

See merge request !41

Fix the interaction list building for a float32 tree.

Closes #21

See merge request inducer/boxtree!38

Closes #21.

Fix from_sep_smaller_min_nsources_cumul for trees without extent.

See merge request inducer/boxtree!37

When extents were turned off, a nonzero
from_sep_smaller_min_nsources_cumul would lead to boxes being silently
ignored during interaction list construction.

This change fixes this problem and also adds a test for
from_sep_smaller_min_nsources_cumul.

Related: This caused inducer/pytential#83 (which turned out to be a
real bug and not a cache problem)

Fix list 3 documentation typo

See merge request inducer/boxtree!36

Fmmlib k rscale

See merge request !31

l^2 stickout tracking

See merge request inducer/boxtree!28