add a few potential tests for the pwdSimulator

Second verse, same at the first:

Sorta WIP. (In other words: the simulator is still marinating in my brain, and I may think of more and/or reconsider these tests.)

First two tests I added might be more for points of discussion, but I believe the third (re: settings change during a run of scheduled basals), which currently fails, poses more of a problem.

Whenever you're ready to discuss @cheddar @kentquirk
We don't need the simulator to adjust the duration of the first scheduled, the API does that for us.  It's the job of the simulator to generate the events that we would want a pump/etc. to push out to the API, not to generate the full-on "correct" set of data points for visualization.