TODO

fkumount
--------

 - Recursively get rid of sub-mounts
 - Support umounting of devices; track down all mount points
   at which this device is mounted
      Caveat: Mount namespaces?
                 - How to detect (bind-mounted /proc/.../ns/mnt
                                  kept around even if empty)
                 - attach to mount ns only in Linux 3.8)
 - Detect bind mounts
   (mountinfo utility called does not support bind mounts)
 - Parse /proc/.../mountinfo directly
   (in order to e.g. detect bind mounts, recursive sub-mounts, ...)
 - NFS kernel server exports
 - Loop devices inside the mount point
   (no process but still keeps mount point busy)
 - Allow passing of -f flag to umount (if NFS server hangs)
   (Note: -f is useless if busy, that's why it's not done so far.)
 - Rewrite in C (?)
      Pro:    doesn't need Python
      Contra: more complex
 - Create utility similar to fkumount which only shows in what
   manner a mount point is busy (processes, loop devices, submounts,
   etc.) so that an administrator might first check what's going on
   before actually killing it.

detect-debmirror
----------------

 - Detect if this is even a Debian variant (python-apt could be
   installed on RPM/other distros, then no essential packages
   will be installed according to APT)
 - Probaby rewrite in C++ to use the APT API
   (python-apt is useful but still far too much in flux)