add offline functionality by making this a PWA

- added favicons
- added manifest
- split javascript into main.js and elevators.js

main.js

@@ -0,0 +1,41 @@
+const version = '0.6.0'
+const minorVersion = version.split('.').splice(0, 2).join('.');
+const numberFormat = new Intl.NumberFormat('de-DE', {
+    maximumFractionDigits: 1
+});
+
+Object.defineProperty(String.prototype, 'capitalize', {
+    value: function () {
+        return this.charAt(0).toUpperCase() + this.toLowerCase().slice(1);
+    },
+    enumerable: false
+});
+
+const dateTimeStyle = new Intl.DateTimeFormat('de-DE', {
+    dateStyle: 'medium',
+    timeStyle: 'medium',
+    timeZone: 'Europe/Berlin',
+})
+
+// set version
+document.querySelector('#version').innerHTML = `v${version}`;
+
+
+function openDialog(selector) {
+    document.querySelector('body').classList.add('has-dialog')
+    document.querySelector('#dialog_layer').classList.add('active')
+    document.querySelector(selector).classList.remove('hidden')
+}
+
+function closeDialog(selector) {
+    document.querySelector('body').classList.remove('has-dialog')
+    document.querySelector('#dialog_layer').classList.remove('active')
+    document.querySelector(selector).classList.add('hidden')
+}
+
+if ("serviceWorker" in navigator) {
+    console.log('installing sw');
+    navigator.serviceWorker.register("/sw.js").then((registration) => {
+        console.log('done installing sw');
+    });
+}