staging: add mausezahn staging directory

After some back and forth, we decided that it is easier to maintain
mausezahn in a staging directory until it is fully reworked and
cleaned up to be ready to be fully integrated. This way, it is better
than having it in a separate branch, and we can also accept patches
from outside more easily. Also, while at it, fix up some function
mismatches with libcli.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>