A higher-level interface

[jtheisen]

We want an interface to reconciler that combines context creation with the various calls to Reconcile and other functions.

In particular, a higher-level function to save data using reconciler should

1. call Reconcile
2. call SaveChanges
3. decycle and blacken the attached entity graph

The advantage would be that this gives write operations against the database which are

• powerful enough to cover most use cases but
• simple enough to be able to run in one transaction, and to be serialized to be sent over the wire

The second advantage regarding transactions is also a plus in the light of Azure SQL Databases recommending all requests to the database using a retry policy, and arbitrary combinations of database writes with contexts spread over long code paths isn't easy to retry.