This first patch is a straight refactoring so that other modules do not touch the FileList internals. 

This is done in two steps. First, we remove references to inversedict etc. from outside FileList.

Second, we run all notifications through FileList. So for example when the config dialog wants to notify all editors of changes, it previously walked through the list of windows and called various editor methods directly. Now, the config dialog asks FileList to notify all editors. Each editor implements the callback to make the needed changes. 

Same code, just moved to a more appropriate place. The config dialog no longer needs any knowledge of FileList or of EditorWindow. Later more of these sorts of callbacks will be added. Doing it this way provides a framework where different components might respond differently to these notifications.