Add multi_file option to XDMF
Merged master into chris/xdmf-multiple-h5
Handle dolfin::la_index type dynamically in SWIG/NumPy wrappers
Some type clean ups in SCOTCH interface and turn on graph checking (for debugging)
Merge branch 'chris/xdmf-multiple-h5'
Merge branch 'garth/fix-64-bit-issues'