Avoid graph loops in local dof ordering and add HDF5 64-bit int type
Check size of 'size_t' at configure and adjust types in SWIG layer accordingly
Relax check in test on float equality.

Check was on number of places, and the rounding used could trigger a failure for tiny changes in output.
Small doc fixes.
tiny fix to cast a 0 to std::size_t
Merge branch 'garth/fix-64-bit-issues' of ssh://bitbucket.org/fenics-project/dolfin into garth/fix-64-bit-issues