Makefile.in: autodep stuff

dh.c: change format to binary from decimal string (without introducing
endianness problems)

netlink.c: investigate why 'default' routes don't appear to work
(reported by JDA).

slip.c: detect failure of userv-ipif to start.

tun.c: jdamery reports tun-old code works on Linux-2.2.
Unresolved problem with ioctl(TUNSETIFF) sometimes returning EINVAL, seems
to be related to early 2.4.x (x<=5) series kernels. 2.4.9 and above seem ok;
2.4.[678] untested.

random.c: test

rsa.c: check padding type, change format to binary from decimal string
(without introducing endianness problems)

site.c: the site_incoming() routing could be implemented much more
cleanly using a table. There's still quite a lot of redundancy in this
file. Abandon key exchanges when a bad packet is received. Modify
protocol to include version fields, as described in the NOTES file.

transform.c: make generic

util.c: sort out logging

sha1.c: test

General: separate the transforms in transform.c into multiple parts,
which can then be combined in the configuration file.  Will allow the
user to plug in different block ciphers, invent an authenticity-only
mode, etc.

Signal handling! Really just cope with SIGCHLD and SIGTERM. Possibly
use SIGUSR1/2 for prodding things.

Write scripts to generate the 'real' sites file from a less-expressive
version that's more easily checked by external tools.