Move long exposure calculations to science camera class
At the moment, the long exposure calculations are performed in the simulation loop. It would make more sense to let the science camera class take care of it directly. The way, long exposure Strehl could be adapted to the type of science camera.
Any objection to a PR that would make this change?
That would be fine.
The only reason I kept the cumulative science image out of the science object originally is because I didn't want the object to effectively change with time. I think thats acceptable though given the benefits it will bring. Also, since I made that decision I've changed the WFS so that it can have a exposure time lasting a number of simulation iterations too, so the change would be consistent with that.