non-marked parts don't count towards anyAnswered

Questions containing information only parts began their lives as "wrong"
because the information parts were wrongly being included in the "any
answered" determination. Only parts which do marking contribute to
anyAnswered now.

themes/default/files/scripts/question-display.js

@@ -246,7 +246,7 @@ Numbas.queueScript('question-display',['display-base','jme-variables','xml','sch
             var anyAnswered = false;
             for(var i=0;i<q.parts.length;i++)
             {
-                anyAnswered = anyAnswered || q.parts[i].answered;
+                anyAnswered = anyAnswered || (q.parts[i].doesMarking && q.parts[i].answered);
             }
             this.anyAnswered(anyAnswered);
         },