Added tag 0.2.0 for changeset 4136cc0bf64d

pkg: prepare 0.2

doc: add information on the schema initialisation

... and an advice for usage as a cheap key-value store.

api: add a delete method

Added tag 0.1.0 for changeset ffa6ae709057

full namespace support

do not forget to update idate on update

fix grotty mistake in set

exhibit bug

make the schema/namespace configurable

key: use an indexable field

switch to sqlalchemy.engine since pgengine is still immature

api: have a convenient `getorset` method

lock per key

cli: provide an `init-db` command

This will install (and if asked reset) the cache namespace and tables.

a minimal db cache for byte strings

Uses postgres byte arrays for keys and values storage.
Entries have a lifetime.

Mutual exclusion access is handled with a transaction advisory lock.