MenuSorter: initial implementation

* Menus are now sanely configurable
* Custom separator placement for clearer menus

frontend/apps/reader/modules/readerfooter.lua

@@ -325,10 +325,10 @@ local option_titles = {
 
 function ReaderFooter:addToMainMenu(tab_item_table)
     local sub_items = {}
-    table.insert(tab_item_table.setting, {
+    self.ui.menu.menu_items["status_bar"] = {
         text = _("Status bar"),
         sub_item_table = sub_items,
-    })
+    }
 
     -- menu item to fake footer tapping when touch area is disabled
     if Geom:new{