Begun implimentation of a really good thread control interface.

Begun implimentation of a really good thread control interface.
As it turns out it impliments a lot of what eCrash does to track threads
though I didn't know it at the time. To check it out look in sysdep.c
and search on CtdlThread. That will get you close.
At the moment nothing makes use of this code.
A handy side effect is a thread safe sleep mechanism that will sleep
the current thread untill some other thread sleeps or it times out, needs a
bit more work to make it sleep any thread without waking when another
thread sleeps.
Also fixed a potential memory leak or two in the old thread code.