equal and indexof need to support comparing items of differnet types, ie string vs number. this is needed because numeric ids stored in val() are strings and need to be compared against data ids which are numbers. fixes #840

select2.js

@@ -103,7 +103,9 @@ the specific language governing permissions and limitations under the Apache Lic
 
     function indexOf(value, array) {
         var i = 0, l = array.length;
-        for (; i < l; i = i + 1) if (value === array[i]) return i;
+        for (; i < l; i = i + 1) {
+            if (equal(value, array[i])) return i;
+        }
         return -1;
     }
 
@@ -113,7 +115,12 @@ the specific language governing permissions and limitations under the Apache Lic
      * @param b
      */
     function equal(a, b) {
-        return a===b;
+        if (a === b) return true;
+        if (a === undefined || b === undefined) return false;
+        if (a === null || b === null) return false;
+        if (a.constructor === String) return a === b+'';
+        if (b.constructor === String) return b === a+'';
+        return false;
     }
 
     /**