Several improvements of AutoFrontlight plugin and enable it by default (#2975)

* Force refresh when kindle is out of screensaver or usb is unpluged.

* Improve AutoFrontlight

* More plugins sub menu

* Last brightness should always be updated

* Finish autofrontlight improvement and enable it by default.

* More tets

* onFlushSettings

* MenuSorter can now correctly sort sub menus

frontend/ui/elements/reader_menu_order.lua

@@ -52,16 +52,21 @@ local order = {
         "read_timer",
         "calibre_wireless_connection",
         "evernote",
-        "keep_alive",
-        "frontlight_gesture_controller",
         "statistics",
-        "battery_statistics",
-        "storage_stat",
-        "synchronize_time",
         "progress_sync",
         "zsync",
         "news_downloader",
+        "----------------------------",
+        "more_plugins",
+    },
+    more_plugins = {
+        "auto_frontlight",
+        "frontlight_gesture_controller",
+        "battery_statistics",
+        "synchronize_time",
+        "keep_alive",
         "terminal",
+        "storage_stat",
     },
     search = {
         "dictionary_lookup",