Updated doc strings & removed mc version of 2op1t

Also:
-changed some instances tlist to taulist for clarification
-changed normalized correlation functions to steady state only

I made a noticed a few mistakes in the docstrings and now I think all the inconsistencies are fixed.

Re the mc correlator:

It looks to me like the quantum regression theorem was attempted to be applied here but the initial condition requires a density matrix. However, the MC method only takes an initial condition as a state so this would not work in general. I suppose in principle there could be special cases that work, but I think the MC correlator needs a different technique.
here instead of having the solver specific parameters n1traj and n2traj as arguments, I would prefer if you used the ntraj in options for this purpose. You can let Options().ntraj be a list to specify both [n1traj, n2traj], or if it is an integer it could mean n1traj = n2traj = Options().ntraj