fix bug where spost and spre results in type oper instead of super
remove typo
Initial stab at addressing qutip/qutip#88.

This is untested so far, but is mainly to demonstrate a
proposed design approach for addressing superoperator metadata,
and how this might be used to make more robust and useful
superoperator conversion functions.
Fixed silly mistakes in previous commit.
Added iscptp, to_super and support for printing choi, super.
Added unit tests for new metadata.
Fixed missing type= in kraus conversion.
Merge pull request #89 from jrjohansson/fix-spost-spre-type

Fix spost spre type
Refactored type='super' and type='choi' in line w/ #88.

New attribute uses superrep='super' and superrep='choi' instead.
Added to_kraus, average_gate_fidelity as example of new superrep attr.
Addressed comments by @jrjohansson on PR #90.
Added test of average_gate_fidelity.
Fixed Py3k compatibility, slow computation in __str__ and _repr_latex_.
Merge pull request #90 from cgranade/feature-supermeta

Implementation of type="super" and type="choi" distinction.
added ipython display hook for improved behavior in the ipython notebook. restructured management of fig/axes
minor fix for backwards compatibility
activate SVG rendering
bug fix: add _t to numpy types to prevent cython error. minor code cleanup
remove warning about reusing rhs function. that warning should go into the docs instead.
fixed string escape problems