rdiff-backup-fs imported

[ewl+rdiffbackup]

Hi,

rdiff-backup-fs was an archived project [1] to create a userspace (fuse) 
file system for a backup repo created by rdiff-backup.

I have neither time nor the necessary skills to revive the project but 
the concept is cool so I imported the code [2].

Anybody having some C skills, feel free to stand up and look if the code 
is worth anything and can be revived for modern kernels/Linux. Pull 
requests very welcome!

Happy hacking,
Eric

[1] https://code.google.com/archive/p/rdiff-backup-fs
[2] https://github.com/rdiff-backup/rdiff-backup-fs