bbkh: replace `big` with `little`, major bugfix...

... some cleanup.
index: replace lsm-db with plyvel...

... except for pypi.okvslite part because I am lazy.
pool_for_each_par_map: keep memory footprint under control.
typofix: try leveldb via plyvel
typofix: do not use a lock to serialize...

... instead use the progress callback. That will avoid the
multi-processus lock, and the open, start transaction, commit,
typofix: try to use multiple process to create index.
typofix: try bigram + trigram...

... way too slow.
typofix - varia

- do not hash digits (trial), and punctutation found in package names,

- rename magic numbers, and first try at documentation,

- try to fix merkletree traversal left-right instead or right left,

- remave spacy, and replace unknown chars with space,

- fix strinc: bytes[n] return an integer, bytes[n:] return bytes,

- improve forward and backward search: score at most 10 times the
  limit of candidates, keep those with a fuzzywuzzy ration superior to

- use bbk.search inside sudopython-typofix.py.

Note: chars with string.digits give better results for an unknown

- simplify regex because strings are lower case,

- remove commented code,

- use summary and description,

- only store documents that have at least one stem.
ZERO is easier to the mind than -infinity
poetry export -f requirements.txt --output requirements.txt --dev
LICENSE: add it (gplv3)
Initial version.
LICENSE: remove it, it must be GPLv3.
combinatorix with query parser.