Add localization

Sources/AdwaitaTemplate.swift

@@ -11,7 +11,7 @@ struct AdwaitaTemplate: App {
 
     var scene: Scene {
         Window(id: "main") { window in
-            Text("Hello, world!")
+            Text(Loc.helloWorld)
                 .padding()
                 .topToolbar {
                     ToolbarView(app: app, window: window)

Sources/Localized.yml

@@ -0,0 +1,17 @@
+default: en
+
+helloWorld:
+    en: Hello, world!
+    de: Hallo, Welt!
+
+newWindow:
+    en: New Window
+    de: Neues Fenster
+
+closeWindow:
+    en: Close Window
+    de: Fenster schliessen
+
+quit:
+    en: Quit
+    de: Verlassen

Sources/ToolbarView.swift

@@ -8,16 +8,16 @@ struct ToolbarView: View {
     var view: Body {
         HeaderBar.end {
             Menu(icon: .default(icon: .openMenu), app: app, window: window) {
-                MenuButton("New Window", window: false) {
+                MenuButton(Loc.newWindow, window: false) {
                     app.addWindow("main")
                 }
                 .keyboardShortcut("n".ctrl())
-                MenuButton("Close Window") {
+                MenuButton(Loc.closeWindow) {
                     window.close()
                 }
                 .keyboardShortcut("w".ctrl())
                 MenuSection {
-                    MenuButton("Quit", window: false) {
+                    MenuButton(Loc.quit, window: false) {
                         app.quit()
                     }
                     .keyboardShortcut("q".ctrl())