add toogle button for signal led in http frontend

firmware/fsdata/fs/index.html

@@ -109,6 +109,19 @@
                     <canvas id="chartCanvas" style="height:100px"></canvas>
                 </article>
             </div>
+            <div>
+                <article class="card">
+                    <header>
+                        <h3>I/O</h3>
+                    </header>
+                    <footer>
+                        <label>
+                            <input type="checkbox" name="onoffswitch" id="led-switch" onclick="gpio()">
+                            <span class="toggle button">toggle signal led</span>
+                        </label>
+                    </footer>
+                </article>
+            </div>
         </div>
     </section>
 </main>

firmware/lux.cpp

@@ -17,7 +17,7 @@ const int gpio4 = 4;
 const int gpio5 = 5;
 
 extern "C" void signal_led(bool state) {
-    gpio_write(signal_led_pin, state);
+    gpio_write(signal_led_pin, !state);
 }
 
 extern "C" void lux_task(void *pvParameters) {

firmware/web.cpp

@@ -226,6 +226,16 @@ void websocket_cb(struct tcp_pcb *pcb, char *data, u16_t data_len, uint8_t mode)
     char cmd = '0';
 
     switch (data[0]) {
+        case 'D': // Disable LED
+            signal_led(false);
+            val = 1;
+            cmd = 'G';
+            break;
+        case 'E': // Enable LED
+            signal_led(true);
+            val = 0;
+            cmd = 'G';
+            break;
         default:
             printf("[websocket_callback]:\n%.*s\n", (int) data_len, (char *) data);
             printf("Unknown command\n");