SFTP based chroniton access
Support for SFTP based file transfer to/from Chronitons, including read-only access to the storage state of moments.
Add support for the SFTP SSH sub-system for access to Chroniton filesystems. The normal mode should be to provide some kind of synthetic file hierarchy, perhaps split into live/historical, and own/other so that a very large list of timestreams is not transmitted to the user. If a command is provided (i.e. via #7), the scope provided should be honored.
Read-only access is straightforward, but, read-write access presents additional challenges: they must be captured in some way as session data, just like terminal sessions. For large bulk file transfers, this could just be a log, but if someone is e.g. using a text editor over SFTP, the contents of deltas would be very important.