Backport autosort for interpolating structures.
More bug fixes for autosort. Also added more robust unittests using
random.shuffle.
Fix unittest.
Mods to speed up Specie comparison.
Merge branch 'master' into surface

Conflicts:
	pymatgen/core/structure.py
	pymatgen/core/tests/test_structure.py
Add get_sorted_structure to surface.