Replace hexToRgb function to work with legacy mobile browsers

pyleds/templates/index.html

@@ -7,6 +7,7 @@
     <link rel="stylesheet" href="custom.css">
 
     <script type="text/javascript">
+        'use strict';
         function hexToRgb(value) {
             var aRgbHex = value.substring(1).match(/.{1,2}/g);
             var aRgb = [
@@ -55,7 +56,7 @@
             document.getElementById('tempo').value = status.features.tempo.bpm;
             let regions = status.features.region;
             let regLen = regions.length;
-            for(i = 0; i < regLen; i++) {
+            for(let i = 0; i < regLen; i++) {
                 if (regions[i]) {
                     document.getElementById('region_' + i).classList.remove('region_off');
                 } else {