allow rectangular matrices in linear_assignment
bugfix to linear_assignment
major overhauls to structure_matcher. Still needs more unit tests
Merge branch 'master' into structure_matcher

Conflicts:
	pymatgen/analysis/structure_matcher.py
some cleanup and refactoring of structure_matcher
Merge branch 'master' into structure_matcher
added more unittests for structure matching
check structure hash in structure_matcher.fit
Merge branch 'master' into structure_matcher
added unittest for StructureMatcher._get_supercell_size
some structure_matcher cleanup, clarification on mapping properties