v0.9.0

• Sparse blocks are no longer explicitly represented in the database. This greatly speeds up the initial step
  of backup creation if the backup is based on an older version, and a lot of the blocks are sparse. It also reduces
  database size and speeds up database operations overall due to the reduced number of rows in the blocks table. No
  database migration is necessary, but the changed representation will only apply to newly created versions.

• Implement benji storage-usage command. See the documentation on how the usage is calculated and its inherent
  limitations.

• For the rbd and rbdaio IO modules add a feature to pass all Ceph credentials as part of the URL of the
  benji backup command. This can also be used to pass other Ceph configuration options, and it is also possible
  to override the client_identifier set in Benji's configuration file. This allows Benji to connect to any
  Ceph cluster without setting up /etc/ceph/ceph.conf beforehand. See the documentation for the full URL syntax.

• benji enforce now skips removed or otherwise unavailable versions and continues with the removal.

• NBD server: The block cache is split up into a block cache and a copy-on-write store for changed blocks. For the
  block cache a maximum size can be specified and least frequently used blocks are evicted if the cache gets full.
  Some adjustments are needed to Benji's configuration due to this change. See etc/benji.yaml for an example.