Add settings to control sounds

lib/app_settings.dart

@@ -0,0 +1,38 @@
+/*
+ * Class for managing app-level configuration options
+ */
+
+import 'package:sembast/sembast.dart';
+import 'package:InvenTree/preferences.dart';
+
+class InvenTreeSettingsManager {
+
+  final store = StoreRef("settings");
+
+  Future<Database> get _db async => await InvenTreePreferencesDB.instance.database;
+
+  Future<dynamic> getValue(String key, dynamic backup) async {
+
+    final value = await store.record(key).get(await _db);
+
+    if (value == null) {
+      return backup;
+    }
+
+    return value;
+  }
+
+  Future<void> setValue(String key, dynamic value) async {
+
+    await store.record(key).put(await _db, value);
+  }
+
+  // Ensure we only ever create a single instance of this class
+  static final InvenTreeSettingsManager _manager = new InvenTreeSettingsManager._internal();
+
+  factory InvenTreeSettingsManager() {
+    return _manager;
+  }
+
+  InvenTreeSettingsManager._internal();
+}