Add cleanness tracker.
Split LocalSharder into a package.
Don't double record in cleanness tracker.
Keep track of cleanness in LocalSharder.
Add snapshotting for CleannessTracker.
Make sure that we always mark it as unclean.
Move Shutdown out of LocalSharder's instance.
Use local sharder in context actor.
Add unknownCommand error.
Ack ContextActor shutdown.
Fix subscription setup in bezug.
Factory methods for properly types Aggregate/PM constructs.
Add BezugContext with command and event supertype.
Add BezugSpec.