Msd

* leave it to PyYAML to determine file encoding (39)

* reads in YAML format as well as sqlite (36)
* fixes rows with null or missing primary key values (37)

* eliminated single-character company names/keys (33)
* use canonical company/brand when building category table (34)
* output now uses NFC unicode normalization, not NFKD (32)
* fix "a/s" (30) and "Pvt Ltd" (12) company suffixes
* custom corrections: make "Pet" and "Restaurant" categories plural (9)

* fix severe bug in select_groups() that silently dropped data (27)

* setup.py includes dependencies in install_requires