Cleanup and commenting of superop_reps.
Added start of chi matrix support.
Added new unit tests.
Fixed previous commit to this file.
Merged from upstream/master.
Fixed circular dependance introduced by recent merge.
Merge branch 'feature-supertests' into feature-chi

Conflicts:
	qutip/tests/test_superop_reps.py
Fixed problems introduced by merge.
Fixed chi superrep.
Merge branch 'master' into feature-chi
Fixed import for Py3k.
Merge pull request #97 from cgranade/feature-chi

Add chi-matrix support to type="super"