Some time ago the save+restore commands were added to ip route (git
id f4ff11e3, Add ip route save/restore). These two save the raw rtnl
stream into a file and restore one (reading it from stdin).

The problem is that there's no way to get the contents of the dump
file in a human readable form. The proposal is to add a command that
reads the rtnl stream from stdin and prints the data in a way the
usual "ip route list" does?

changes since v1:

* Take the magic at the beginning of the dump file into account
* Check for stdin (the dump is taken from) is not a tty
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>