Make the favicon conform to various standards

Thanks, realfavicongenerator.net!

Closes imagej#214.

Author: ctrueden

_includes/layout/favicon

@@ -0,0 +1,15 @@
+{%- comment -%}
+Credit to https://realfavicongenerator.net/
+{%- endcomment -%}
+
+    <link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
+    <link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
+    <link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
+    <link rel="manifest" href="/site.webmanifest">
+    <link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
+    <meta name="msapplication-TileColor" content="#da532c">
+    <meta name="theme-color" content="#ffffff">
+
+{%- comment -%}
+# vi:syntax=liquid
+{%- endcomment -%}

_includes/layout/head

@@ -1,7 +1,7 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=3" />
     {% include layout/onebox-info %}
-    <link rel="shortcut icon" href="/favicon.png">
+    {% include layout/favicon %}
     <link rel="stylesheet" href="/assets/css/lightbox.min.css" />
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/instantsearch.css@7/themes/algolia-min.css"/>
     <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/[email protected]/dist/dygraph.min.js"></script>

android-chrome-192x192.png

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<browserconfig>
+    <msapplication>
+        <tile>
+            <square150x150logo src="/mstile-150x150.png"/>
+            <TileColor>#da532c</TileColor>
+        </tile>
+    </msapplication>
+</browserconfig>

android-chrome-256x256.png

@@ -0,0 +1,19 @@
+{
+    "name": "ImageJ Wiki",
+    "short_name": "ImageJ",
+    "icons": [
+        {
+            "src": "/android-chrome-192x192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "/android-chrome-256x256.png",
+            "sizes": "256x256",
+            "type": "image/png"
+        }
+    ],
+    "theme_color": "#ffffff",
+    "background_color": "#ffffff",
+    "display": "standalone"
+}