make sure we are robust in the face of fancy namespace names

build: run ruff

cleanup imports

an initial continuous integration spec

Add missing `pytz` dependency, pin sqlalchemy to 1.x

cli/migrate-to-kv-store: a command to upgrade the local schema with the new kv stores

doc/readme: document the new kvstore and vkvstore

api/vkvstore: .set gets a public insertion_date parameter and a safety assertion

api/vkvstore: provide an access to the version timestamps

api/vkvstore: make sure we get the right version if asked

schema: make sure the idate field is unique

api/vkvstore: a versioned key/value store

hgignore: prune more things

api/kvstore: a .keys() method

api/kvstore: a simple key/value store with string keys and json values

api/cache: allow fancy namespaces with quoting

api/cache: accept string keys