Make error message on lacking Python library more informative

Patch contributed by Rafael Laboissiere


git-svn-id: svn+ssh://svn.code.sf.net/p/xmds/code/trunk/xpdeint@2955 41b19578-b77a-4e3b-9682-c8570d237623
Check for HDF5 & find compile flags by using 'h5cc'.

git-svn-id: svn+ssh://svn.code.sf.net/p/xmds/code/trunk/xpdeint@2956 41b19578-b77a-4e3b-9682-c8570d237623