Merge pull request #649 from RosettaCommons/vmullig/mpi_c_bool_issue
Switching all instances of MPI_C_BOOL to MPI_CHAR
Switching all instances of MPI_C_BOOL to MPI_CHAR to fix compilation issues on certain systems. I'm using MPI_CHAR for my dummy/acknowledgement signal because a char is the one datatype that's guaranteed to be one byte wide in the C++ standard, and I don't want to waste time sending more than one byte for an acknowledgement signal. (Unfortunately, the C standard did NOT originally have a boolean data type, so MPI_C_BOOL is not always defined in all flavours of MPI, apparently. Still, a C++ bool is 8 bits wide rather than 1 bit, since the smallest memory space that one can address is a byte, and a bool* wouldn't make sense if bools were 1 bit. This means that I'm not really losing anything by switchng this to a char.)
No test changes expected.