add portals-shmem src subdir that will be refactored to use MPI-3 instead
rename ptl4 to mpi3 and rm xpmem
i don't know what this was for but i hate perl too much to care
gutted portals4 shmem impl, MPI still TODO
test code taken from stackoverflow
shmem implementation from scratch in flight
original dlmalloc from http://gee.cs.oswego.edu/pub/misc/malloc-2.8.4.c for diffing
commit the diff for easy reference
lots of hacking on mpi symmetric heap business
config.h is empty to allow to compile, same for shmem.h