This release adds shards support, now Xapiand creates sharded databases by default.
Added
- Sharding support added
    - By default there are now five shards per index
- Shards are put inside subdirectories with the shard number prefixed with .__
 
Changed
- BREAKING: All schemas are now foreign by default, and get put inside the databases indexes
- BREAKING: Databases indexes directories work like shards and thus were renamed
              from .xapiand/<node_name>to.xapiand/index/.__<node_idx>
