Fix for issues with resetting saved search

Prior to this fix, when you would open a saved search, then add some columns (without saving), then click on the reset button next to the saved search title, the columns wouldn't reset properly (you'd still see the columns you added in the field list on the left), and everything would get really out of whack.

This fix invokes `setFields` each time you click the reset button, which properly resets the added fields and sets their `display` property (which wasn't happening prior to this change).

Closes #2012.