Replace division with mult in time-dependent a_op terms (#698)
Replace division with mult in time-dependent a_op terms (#698)

* faster rcm

* update norms

* Remove rcm bucky test

the use of int_argsort makes the exact perm array platform dependent.

* Replace division with multi

cgranade/qutip,qutip/qutip,cgranade/qutip,qutip/qutip