Move JavaScript code into explicit namespaces

This cleans up the global namespace by explicitly exporting shared values. All html and JavaScript files have been converted to use explicit exports except for client.js and mocha-init.js

src/webui/www/private/scripts/preferences.js

@@ -28,20 +28,34 @@
 
 'use strict';
 
-const LocalPreferencesClass = new Class({
-    get: function(key, defaultValue) {
-        const value = localStorage.getItem(key);
-        return ((value === null) && (defaultValue !== undefined))
-            ? defaultValue
-            : value;
-    },
+if (window.qBittorrent === undefined) {
+    window.qBittorrent = {};
+}
 
-    set: function(key, value) {
-        try {
-            localStorage.setItem(key, value);
+window.qBittorrent.LocalPreferences = (function() {
+    const exports = function() {
+        return {
+            LocalPreferencesClass: LocalPreferencesClass
+        };
+    };
+
+    const LocalPreferencesClass = new Class({
+        get: function(key, defaultValue) {
+            const value = localStorage.getItem(key);
+            return ((value === null) && (defaultValue !== undefined))
+                ? defaultValue
+                : value;
+        },
+
+        set: function(key, value) {
+            try {
+                localStorage.setItem(key, value);
+            }
+            catch (err) {
+                console.error(err);
+            }
         }
-        catch (err) {
-            console.error(err);
-        }
-    }
-})
+    })
+
+    return exports();
+})();