improved html and navi, navi is visible even when API dies #660

reduced maximum allowed JSON size for API to 6000Bytes #660
small fix: output command at `prepareDevInformCmd` #692
improved inverter handling for MQTT #671

src/web/html/includes/nav.html

@@ -0,0 +1,27 @@
+<div class="topnav">
+    <a href="/" class="title">AhoyDTU</a>
+    <a href="javascript:void(0);" class="icon" onclick="topnav()">
+        <span></span>
+        <span></span>
+        <span></span>
+    </a>
+    <div id="topnav" class="mobile">
+        <div id="topnav" class="mobile">
+            <a id="nav2" class="hide" href="/live">Live</a>
+            <a id="nav3" class="hide" href="/serial">Serial / Control</a>
+            <a id="nav4" class="hide" href="/setup">Settings</a>
+            <span class="seperator"></span>
+            <a id="nav5" class="hide" href="/update">Update</a>
+            <a id="nav6" class="hide" href="/system">System</a>
+            <span class="seperator"></span>
+            <a id="nav7" href="/api" target="_blank">REST API</a>
+            <a id="nav8" href="https://ahoydtu.de" target="_blank">Documentation</a>
+            <span class="seperator"></span>
+            <a id="nav0" class="hide" href="/login">Login</a>
+            <a id="nav1" class="hide" href="/logout">Logout</a>
+        </div>
+    </div>
+    <div id="wifiicon" class="info"></div>
+</div>
+
+