clean up of first changes

clean up of all the comments and whatever.
this version splits off the exec name and loads the executable, passing the full command line string down to setup_stack, which still does nothing with it.
this version also includes thread_alive, a preliminary fix for process_wait not actually waiting.  this method loops through the all_list looking for the tid in question, returning whether it's still alive (i.e. in the list) or not.

something's broken with I think the thread_alive loop, which throws a Page Fault exception in the kernel for illegally accessing (actually, just reading...) a page in user context.  So that's not good. Not sure what the deal, will keep testing, first priority is finish the stack construction so that we can actually run these programs!
the error seems to always occur right after start_process "exits" (it doesn't actually, it transfers control to an interrupt context which starts the new thread)