Let user specify the events considered when generating SightNoDaily

[smwoodman]

das_sight currently always uses all of the S/K/M/G events to generate SightNoDaily values. This is regardless of return.events arguments.

The function should be updated to provide some way for the user to specify the events considered when generating SightNoDaily values. Probably simplest/most consistent to use return.events.

Related, because of this, das_sight currently inefficiently always processes all sighing information, rather than filtering based on return.events early. Explore ways to filter earlier to minimize processing.