change default for smoothing_window_correction to 0.5

[bjdebus]

In the robust workflow class, change the default for smoothing_window_correction from 0.8 to 0.5. Will require updating the tests for all workbooks.

[bjdebus]

@adcalpa Please hold off on this for now. I am modifying the robust workflow, and based on how that goes, we may choose a different correction factor as the default.