Update ACE Editor to version 1.2.9

The new ACE editor introduces full support for emojis (and, thereby, UTF-16 characters with high- and low-surrogates). Hence, we can remove our custom fix.

Further, this update will allow emojis to be used in pair programming sessions.

vendor/assets/javascripts/ace/mode-gcode.js

@@ -73,6 +73,7 @@ define("ace/mode/gcode",["require","exports","module","ace/lib/oop","ace/mode/te
 
     var Mode = function() {
         this.HighlightRules = GcodeHighlightRules;
+        this.$behaviour = this.$defaultBehaviour;
     };
     oop.inherits(Mode, TextMode);