nos-tun(8) on FreeBSD

The text 518773d4d30b, as FreeBSD 3.5.1-RELEASE, FreeBSD 3.5-RELEASE, FreeBSD 3.4-RELEASE, FreeBSD 3.3-RELEASE shipped it.

implement ``nos'' or ``ka9q'' style IP over IP tunnel

nos-tun(8) on FreeBSD now