ecmascript/page: Add toString method for page.Item object
ecmascript: Add Showtime.propDestroy()
ecmascript/page: Add Item.destroy() method
ecmascript: Add Showtime.propIsSame() method
ecmascript: Add support for page.reorderer() callback

Fixes #2431
ecmascript/page: Fix more for item move support
ecmascript: Make es_get_native_obj_nothrow() more robust
ecmascript/page.js: make page.getItems() return a copy of the items array
Update zh_CN translation
Merge pull request #178 from RuralHunter/master

Update zh_CN translation
Update lang files