Highlight error in ACE

[sameersingh]

One problem is Moro is configured to only return HTML, so I easily can print the error in a better way so that the relevant line is copied, for example.

If I can send the correct info, then the marker can be added to the editor quite easily in javascript, which will be removed as soon as the user change the text of the editor. For future reference: https://groups.google.com/forum/#!topic/ace-discuss/joAFrXwWLX8 and http://stackoverflow.com/questions/23726302/ace-editor-addmarker-throwing-erro