Fixed issue #7976: Date question: keyboard entries not validated

Dev: when using the keyboard on the datepicker,
Dev: in the date/time question, invalid dates could be entered
Dev: and submitted. Added validation for dates.

scripts/date.js

@@ -8,15 +8,36 @@ $(document).ready(function(){
         language=$('#datelanguage'+basename).val();
         datemin=$('#datemin'+basename).val();
         datemax=$('#datemax'+basename).val();
+
         $(e).datepicker({ dateFormat: format,
             showOn: 'both',
             changeYear: true,
             changeMonth: true,
             defaultDate: +0,
             beforeShow: customRange,
             firstDay: "1",
-            duration: 'fast'
-            }, $.datepicker.regional[language]);
+            duration: 'fast',
+            // Validate input. Necessary because datepicker also allows keyboard entry.
+            onClose: function() {
+                format=$('#dateformat'+basename).val();
+                answer=$('#answer'+basename).val();
+                //only validate if the format mask says it's a complete date and only a date
+                var str_regexp = /^[mydMYD]{1,4}[-.\s\/][mydMYD]{1,4}[-.\/\s][mydMYD]{1,4}$/; 
+                var pattern = new RegExp(str_regexp); 
+                if (format.match(pattern)!=null)
+                {
+                    try
+                    {
+                        newvalue=jQuery.datepicker.parseDate(format, answer);
+                    }
+                    catch(error)
+                    {
+                        alert('Date entered is invalid!');
+                        $('#answer'+basename).val("");
+                    }
+                }
+            },
+        }, $.datepicker.regional[language]);
     });
 
     // dropdown dates
@@ -41,7 +62,6 @@ function customRange(input)
     };
 }
 
-
 function dateUpdater() {
 
     if(this.id.substr(0,3)=='yea')