added documentation, moved isherm to istests module, and added type attribute corresponding to whether quantum object is a ket, bra, operator, or super-operator.
added documentation, moved isherm to istests module, and added type attribute corresponding to whether quantum object is a ket, bra, operator, or super-operator.

anubhavvardhan/qutip,qutip/qutip,anubhavvardhan/qutip,cgranade/qutip,cgranade/qutip,zasdfgbnm/qutip,zasdfgbnm/qutip,qutip/qutip