MemoryStore: a little bit of cleanup
Fixed a few XML comments and args names
Added missing PrintLine() in Logging.Exception(...) method
Fixed SliceListStream.Seek(..) method

- implementation seemed to be unfinished ?
Fixed SliceStream that was not passing the cancellationToken to the underlying stream when writing
Marked some methods with the [Pure] attribute
Marked some private fields as read-only
Removed some unnecessary casts
Simplified some lambda expressions
Rewritten some expression using ?? and ?:
Removed unnecessary ToString() and cleaned up / fixed a few String.Format(...)
Fixed FdbOperationContext not combining properly the cancellation tokens in some cases
Removed unnecessary try/catch
Misc code inspection fixes
Logging Filter: record the committed version when CommitAsync completes successfully
Only hookup continuation if the parent task is faulted
Directory Layer: ensure that IEnumerable<> path is only used once, and added FullName property to simplify logging of the full path