Remove some programs which live as atf tests now.

Add a test/example program for using audio/pad in a rump kernel.
It stuffs some nice sounds into the virtual kernel's /dev/audio,
reads the PCM from /dev/pad, and writes the data to stdout from
where it can be piped to audioplay to test that things actually
work.

If you want to know the secret message, you'll just have to run
this program ;)

Add an example/test program for rump bluetooth. This does discovery
and prints the address and name of the first peer encountered (if any):

ubt0 at uhub0 port 1
ubt0: Cambridge Silicon Radio Bluetooth USB Adapter, rev 2.00/19.15, addr 2
device ubt0, addr xx:xx:xx:xx:xx:xx
my peer: yy:yy:yy:yy:yy:yy, major class: 2 (phone)
peer name: Mokia maailmalta

Add a simple tty server which attaches to /dev/ttyU in the rump
kernel and provides the same device on the host with pud(4). I
can succesfully talk to my u3g device using tip(1) against the
server's devices. Some characters are lost here and there, though
(probably a problem with interrupt pipes in ugenhc). Once that
issues is solved, there is no reason why e.g. pppd (chat) could
not be used against the server.

Now, why would anyone want to do this instead of using the kernel
driver directly? Well, for one, on my laptop I run netbsd-5 which
doesn't have a u3g driver which supports the u3g hardware I have.

As anyone with half an eye can see, this is quite copypasted from
umserv and there is plenty of opportunity for uncopypasting for
the eager vi-wielder.

descend into new subdirs

Stick a top-level subdir-makefile here for easy build-testing.