Removed useless import in test_netcdf
 Cosmetic changes.
Merge remote-tracking branch 'mpmaster/master'

Conflicts:
	pymatgen/util/testing.py
Increment version to 2.7.1b.
Merge remote-tracking branch 'mpmaster/master'
Imporve matgenie conversion.
smart_element_or_specie: avoid type-checking, call Element.from_Z if str(obj) represents an integer
Merge remote-tracking branch 'mpmaster/master'
Add very basic unittest for DiffusionAnalyzer.
Merge branch 'master' of https://github.com/gmatteo/pymatgen
Add unittest for smart_element_or_specie.
Various doc improvements.
Minor cleanup.
Minor cleanup.
Improve angle function.
Add append, insert and remove to Structure and Molecule.
Fix unittests.
Add MutableStructure and MutableMolecule.
Port many of the structure_modifier functions to MutableStructure.
Fix unittest.