Added input validation to simulation time

editor/editor.php

@@ -84,7 +84,7 @@
 
             <label for="stop-physics-delay">Amount of time [in seconds] after which the physics simulation is stopped</label>
             </br>
-            <input type="number" value="5" id="stop-physics-delay" name="stop-physics-delay" class="small-width">
+            <input type="number" onkeypress="return (event.charCode !=8 && event.charCode ==0 || (event.charCode >= 48 && event.charCode <= 57))" value="5" id="stop-physics-delay" name="stop-physics-delay" class="small-width">
             </input>
         </div>
     </section>