appwindow: remove RxJS

#389

Author: amezin

ddterm/app/application.js

@@ -171,7 +171,7 @@ const Application = backport.GObject.registerClass(
             this.window = new AppWindow({
                 application: this,
                 decorated: this.decorated,
-                gsettings: this.settings,
+                settings: this.settings,
                 menus,
             });