adds setClass(invert) black theme

adds class string to body, invert(black) is built in
` wm.setClass("invert");`

extras/WiFiManager.template.html

@@ -7,6 +7,23 @@
 <!-- /HTTP_HEAD -->
 <!-- HTTP_STYLE -->
 <style>
+
+body.invert,
+body.invert a,
+body.invert h1 {
+	background-color:black;
+	color:white;
+}
+body.invert .msg{
+	border-top: 1px solid #696969;
+	border-right: 1px solid #696969;
+	border-bottom: 1px solid #696969;
+}
+body.invert .q[role=img] {
+    -webkit-filter: invert(1);
+    filter: invert(1);
+}
+
 .c,
 body {
     text-align: center;
@@ -77,10 +94,7 @@ a:hover {
 .ql .q {
     float: left;
 }
-.qinv .q {
-    -webkit-filter: invert(1);
-    filter: invert(1);
-}
+
 .q:after,
 .q:before {
     content: '';width:16px;height:16px;display:inline-block;background-repeat:no-repeat;background-position: 16px 0;
@@ -150,7 +164,7 @@ button.D{
 <!-- /HTTP_SCRIPT -->
 <!-- HTTP_HEAD_END -->
 	</head>
-	<body>
+	<body class="invert">
 		<div class='wrap'>
 		<!-- <div class='wrap ql qinv'> -->
 <!-- /HTTP_HEAD_END -->