Enhance fioi task wrapper 'wrapper.html' to save task answer only if it has...

Enhance fioi task wrapper 'wrapper.html' to save task answer only if it has been changed from the previous saved answer

tasks/jwinf/wrapper.html

@@ -79,13 +79,23 @@ function getTaskProxyCallback(task) {
     task.load(myLoadViews, loadCallback, ec("task.load"))
   }
 
+  var previous_answer = "";
+
   function getAnswerCallback(answer) {
+    // If the answer did not change since last save, there is nothing to do
+    if (answer == previous_answer) {
+      return;
+    }
+
     console.log("In task.gradeAnswer callback:");
     console.log(answer);
 
     function gradeAnswerCallback(score, message, scoreToken){
       function save_task_callback() {
         console.log("OK transmission");
+
+        // Now we know that the answer has been saved
+        previous_answer = answer;
       };
       function save_task_error() {
         console.log("ERROR transmission");