adding swap button

index.htm

@@ -70,6 +70,7 @@
                 <select id="pointb" name="Point_B">
                   <!-- Options will generated in code -->
                 </select>
+                <button id="swapab" class="btn">Swap</button>
                 <br />    <br />
                 <label for="speed">Travel Speed</label>    <br />
                 <input type="text" id="speed" value="14">    <br />