- add note in BuildIssues about the I_MPI_CC variable, which is needed
when building with Intel-MPI and gcc/clang.
This additional setting is needed since the changes needed to solve
the issue of building scotch with Intel-MPI and icc (issue #434)
means that mpiicc is now being used as the wrapper when compiling
scotch.
- have the FOAM_MPI short name for INTELMPI start with 'impi-' instead
of just the version number.
Intel-MPI is often installed as /opt/intel/impi/4.1.3.049, which
results in 'FOAM_MPI=4.1.3.049' and the mpi flavour is lost.
Prefix these cases with 'impi-'
