Add polling time list and fix minor bugs

Remove FastPriorityQueue because jIO already sorts everything
and gadget.state.message_list_dict[room] is always sorted,
fix the merge algorithm to not use a priority queue at all,
add POLL_DELAY_LIST to customize increasing polling intervals,
add current_refresh_dict as a mutex over refreshChat(),
and add requirements to function docstrings.

bt5/officejs_eyqs/PathTemplateItem/web_page_module/gadget_erp5_page_chat_connect_js.js

@@ -62,7 +62,6 @@
 
 
     /* Render the gadget.
-     * Parameters: nothing
      * Effects: update header, page_title to "Connect to Chat"
      */