http://www.oschina.net/p/ace-editor
https://git.oschina.net/pandao/editor.md/blob/master/editormd.js/?dir=0&filepath=editormd.js&oid=1f18a474ff3798624d13fddb64786570486c4a13&sha=af08536772e34f6ef95870bb4cfd85d09bf1c932
http://www.hyjiacan.com/post/codemirror-config/