- Update to 0.8.0:
* This release contains significant changes related to the naming, format and
structure of internal and external data representations. They derive from the
experience of using Benji in the last few months and from the challenges
uncovered by the ongoing Kubernetes integration efforts. The changes have been
bundled to avoid multiple metadata version changes and migrations.
* Old metadata backups and exports and old object metadata can still be read by
this version of Benji. Existing databases can be migrated to the new database
structure with benji database-migrate. While this process has been tested with
both PostgreSQL and SQLite it is strongly recommended to make a consistent
backup of the database before attempting the migration. The migration process
requires a significant amount of time and disk space when there are a lot of old
backups in the database. The versions and blocks tables are completely recreated
and the old data is moved over. Expect the disk usage to more than double during
the migration.

Database and metadata changes:
* The version of metadata exports has changed from 1.1.0 to 2.0.0. Old
exports (1.0.0 and 1.1.0) can still be imported.
* snapshot_name in the versions table has been renamed to snapshot in the
database and in metadata exports. The long version of the corresponding command
line option has also been renamed from --snapshot-name to --snapshot.
* name in the versions table has been renamed to volume in the database and in metadata exports.
* bytes_dedup in the versions table has been renamed to bytes_deduplicated in the database and in metadata exports.
* id in the blocks table has been renamed to idx in the database and in metadata exports.
* The type of uid in the versions table has been changed from integer to
string. This also affects any metadata exports. This removes the inconsistency
where uid was represented as a string in some places and as an integer in
others. uids are automatically generated for new versions, but there is also
the option to set the uid of a version on backup via the new -u/--uid option.