pthread_test can easily be built for linux

Note the use of misc-compat.h.  Feel free to add things there for other
tests.
pthread_switch: fast user-level context switch

This is just an example of what you can do.  Be a little careful if you
use this in another 2LS, since it short-circuits the rest of
uthread_yield.  I think it is okay as is, but future uthread changes
could cause trouble.  If we really need this behavior, I could build it
in to uthread.c.

Also, this adds an interface to pthreads, such that you can create a
thread, but not start running it yet.  Careful with that, too.
Removed IRQ routing test

Was getting sick of those #warnings during compile.
Adds kill to the monitor

Got tired of procinfo kill PID.  Too much typing.  =)
Monitor access to semaphore debugging info

db sem for print_all_sem_info().  Easier than kfuncing.  Feel free to
add other useful things to db.

Also, this adds that much needed newline to print_all_sem_info().  How
many people have looked at that output and not cursed its unreadability?
Fixes ifconfig issues

On my machine, cs doesn't produce #s/cs before ifconfig tries to mount
it.

Also, cs debugging is pretty loud.  We can turn it on easily if we need
to debug.
Removes ping warnings, tries to use cs

CS doesn't actually work completely.  It'll hang if you:

ash ifconfig
echo debug > cs
ping www.google.com

It's fine that we don't have DNS yet, but CS shouldn't hang forever.
Monitor command bt, alias for backtrace