added explicit types and isherm for qobj methods where the answer is a known value.
added explicit types and isherm for qobj methods where the answer is a known value.

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