async enmlRender; update note title in period save
async enmlRender; update note title in period save

1. make enmlRender.getEnmlFromElement() async and return both enml and
title in the returned promise
2. new enmlRender.get_title() to get title but not enml, also async
3. when save current note periodically, update note's title as well

zenja/markever,zenja/markever