2010.01.21
The next version (experiment 4) will add multiple
event queues as specified in the Nutt lab 8.

2010.01.21
Now this needs some serious test loads. 

2010.01.21
If you're reading this, then you'll see how ridicuously
simple this implementation is.

2010.01.21
Ignore the previous note. Experiment 3 here just uses
sleep_on and wake_up as-is and without anything else.
It all seems to work just fine. Each sleep_on call puts puts
the calling task on the wait queue. The wake_up call wakes up
every task on the wait queue.

If I wanted to just wake up one queued process at a time
I would probably just use wake_up_process. And, figure out
how to dequeue the process from the wait queue.

2010.01.21
Experiment 3 begins with experiment 2 but now sets up
one real event queue to hold waiting processes. The
signal code will release one waiting process in this
version. If there are no processes to release, then
the signal returns without effect.

We'll use the code pulled straight from sleep_on and
wake_up, but without the macros so it is easier to
see what is going on.