Automatic PFS creation

Michael Neumann has come up with a way to automatically create pseudo file systems (PFS) when mirroring a Hammer volume.  Previously, the destination/slave file system would have to be created first; this makes it Just Work.

This means Hammer data streams will be incompatible with versions before and after this change, but it’s not going to damage anything.  Introducing a versioning system into Hammer data streams is an available project…