- export/setenv WM_COMPILER_TYPE as suggested by Mattijs.
- for overall consistency, don't carp about an unset WM_COMPILER_TYPE,
since this would only be on the first instance (prior to the
export/setenv) and would be confusing about why/when this message
may occur.
- reduce clutter: only use (system|ThirdParty) for WM_COMPILER_TYPE.
Drop the old 'OpenFOAM' setting for WM_COMPILER_TYPE, which was
transitional in early 2011.
- make the error messages more meaningful