In many ways, the program this week looks much worse than it did last 
week.  The code has been completely reorganized to allow for multiple 
distinct executables to share resources.  Therefore, rather than 
defining the shared memory image and semaphore names in crossing.c, 
this information has been moved to shared.h.  Routines have also been 
defined that allow for the processes to share semaphore and memory 
group id's using environment variables.  Once again, the program 
currently does little more than execute and immediately terminate.