alias getCanvas to existing getCanvass function

Author: conorhastings

lib/core.js

@@ -66,6 +66,8 @@ module.exports = {
       return this.refs.canvass.getDOMNode();
     };
 
+    classData.getCanvas = classData.getCanvass;
+
     var i;
     for (i=0; i<extras.length; i++) {
       extra(extras[i]);