Merge pull request #264 from TomTranter/develop

Fix bug in trapping and DelaunayCubic logger
- Update docstring tests everywhere...someone removed the >>> import OpenPNM from the beginning of every example, so they weren't working.
- Also added something to the run_tests file to ignore Pyhon/Numpy generated warnings.
Changes to __setitem__ in GenericNetwork and GenericPhase to allow copy.deepcopy(network) to function
- These changes allow the writing of 'pore/throat.all' when they exist as empty lists [ ]
- Prior to this change the __setitem__ was denying the 're'-writing of these dicts
Changed ``== None`` and ``!= None`` to ``is None`` and ``is not None`` everywhere
- Numpy started throwing a 'FutureWarning' about how == will result in elementwise comparisons
- The test suite still works fine
Merge branch 'develop' of https://github.com/PMEAL/OpenPNM into develop
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