add CommWorld status to config_summary.m4
explicitly disable e.g. Parallel::send() without CommWorld
Merge pull request #86 from benkirk/remove_global_parallel

Remove e.g. Paralell::send()
If we don't dupe it, we don't free it

This should fix the failures we're seeing when mpich2/1.4.1 complains
that we're not allowed to free MPI_COMM_WORLD.