Super new speedy checkrestart

This show significant speed increases on systems with a large number of open files by utilising /proc/<pid>/fd and pmap instead of using lsof.

If i could find a way to view memory mapped files for a process in python I would do that, but for now we will fork to pmap instead.

This cannot be merges automatically to our master branch as I want it mergeable with the upstream `debian-tpo/goodies` repo.