* Added new tests validating gotcha wrappers
* Update MPI example to use thread
* Tweaks to mpi-flat test and mpi_gotcha
- enabled MPI_Comm_size and MPI_Comm_rank in mpip so disabled them at runtime
- set test to collapse threads and processes
* Tweak to test and example
- mpi test sets GOTCHA_DEBUG=1 in env
- removed checking for MPI_{Comm_dup,Comm_group,Group_incl}
- tweaked tests so pthread_join is where it is expected
* Remove reliance on MPI_Comm_rank
- read /proc/<PID>/tasks/<PID>/children of parent process to deduce the rank
- Old format relied on user calling MPI_Comm_rank(MPI_COMM_WORLD, ...)
- if MPI_Comm_rank called with subcommunicators only, multiple ranks would write to same file
* Tweak mpi example