Extensibility isn't as good as it should be

[tomasaschan]

You can't build your own event and dbcontext implementation as intended. With these classes defined,

 public class EventMetadata : IMutableEvent<long, long> { ... }

 public class MyCustomDbContext : DbContext, IEventStoreContext<EventMetadata> { ... }

then EntityFrameworkEventStore<long, long, MyCustomDbContext, EventMetadata> fails to compile because EventMetadata doesn't inherit RdbmsEventStore.EntityFramework.Event<long, long>.

This shouldn't be a requirement.