Major progress on revamp

* Deprecated explicit prompt.hjson/general.promptFile, etc.: menu.hjson can simply include any number of files
* All menus and themes, their events, etc. are managed by ThemeManager allowing includes, refs, etc. and much cleaner code

core/config_default.js

@@ -14,7 +14,6 @@ module.exports = () => {
             closedSystem    : false,                    //  is the system closed to new users?
 
             menuFile        : 'menu.hjson',     //  'oputil.js config new' will set this appropriately in config.hjson; may be full path
-            promptFile      : 'prompt.hjson',   //  'oputil.js config new' will set this appropriately in config.hjson; may be full path
             achievementFile : 'achievements.hjson',
         },