Initial support for menus

v2/pkg/menu/mac.go

@@ -0,0 +1,10 @@
+package menu
+
+// DefaultMacMenu returns a default menu including the default
+// Application and Edit menus. Use `.Append()` to add to it.
+func DefaultMacMenu() *Menu {
+	return NewMenuFromItems(
+		AppMenu(),
+		EditMenu(),
+	)
+}