Fixed the off-by-two error in the displays pop-ups on the Applications tab (#251376).

Among the changes:
1. We no longer use Bindings to populate the pop-up menus. Instead, we populate them ourselves.
2. Likewise, we no longer use Bindings to set the pop-up menus' selections, and the pop-up menus do not talk directly to the relevant array controllers. Instead, the pop-ups send action messages to the preference pane, and each action method changes the application's or notification's display setting.
3. The Configure button and table view double-click action now both go through the same method.
4. The action method for activating the Applications tab (see #3) repopulates the displays pop-ups and updates their selections.
5. We now identify the selected display by its bundle name (in the representedObject property of the menu item), instead of by its index.

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 	<string>672</string>

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