Namespace makefile variables
Issue #16
new
Currently can't build on recent Fedora as the installed mpi compiler automatically defines various environment variables including MPI_LIB
this clashes with a variable name used internally by the Makefile and hence my build fails.
I'd propose we should rename these flags as GK_MPI_LIB
etc., this would of course impact all other projects that use the shared Makefiles repo so we'd need agreement across all.