Update codeMirror to 3.16

codemirror-compressed.js is generated at http://codemirror.net/doc/compress.html
includes:
- codemirror.js
- css.js
- htmlmixed.js
- javascript.js
- xml.js
- runmode.js
- searchcursor.js (to enable highlight search term within codemirror"
- overlay.js (to support visible space)

added following custom code when generating the codemirror-compressed.js (to support visible space):

```javascript
CodeMirror.defineMode("visibleSpace", function(config, parserConfig) {
	var visibleSpaceOverlay = {
		token: function(stream, state) {
			var ch = stream.next();
			if (ch == " ") {
				return "space";
			}
			else {
				return null;
			}
		}
	};
	return CodeMirror.overlayMode(CodeMirror.getMode(config, parserConfig.backdrop || "htmlmixed"), visibleSpaceOverlay);
});
```