Minesweeper: Reorganize menus a bit

Move some of the "Game" menu into the app menu, and add a separate menu
for the difficulty setting.

Games/Minesweeper/main.cpp

@@ -48,14 +48,22 @@ int main(int argc, char** argv)
 
  auto app_menu = make<GMenu>("Minesweeper");
 
- RefPtr<GAction> chord_toggler_action;
- chord_toggler_action = GAction::create("Single-click chording", [&](const GAction&) {
+ app_menu->add_action(GAction::create("New game", { Mod_None, Key_F2 }, [field](const GAction&) {
+ field->reset();
+ }));
+
+
+ app_menu->add_separator();
+
+
+ NonnullRefPtr<GAction> chord_toggler_action = GAction::create("Single-click chording", [&](const GAction&) {
  bool toggled = !field->is_single_chording();
  field->set_single_chording(toggled);
  chord_toggler_action->set_checked(toggled);
  });
  chord_toggler_action->set_checkable(true);
  chord_toggler_action->set_checked(field->is_single_chording());
+
  app_menu->add_action(*chord_toggler_action);
  app_menu->add_separator();
 
@@ -65,24 +73,20 @@ int main(int argc, char** argv)
  }));
  menubar->add_menu(move(app_menu));
 
- auto game_menu = make<GMenu>("Game");
- game_menu->add_action(GAction::create("New game", { Mod_None, Key_F2 }, [field](const GAction&) {
- field->reset();
- }));
- game_menu->add_separator();
- game_menu->add_action(GAction::create("Beginner", { Mod_Ctrl, Key_B }, [field](const GAction&) {
+ auto difficulty_menu = make<GMenu>("Difficulty");
+ difficulty_menu->add_action(GAction::create("Beginner", { Mod_Ctrl, Key_B }, [field](const GAction&) {
  field->set_field_size(9, 9, 10);
  }));
- game_menu->add_action(GAction::create("Intermediate", { Mod_Ctrl, Key_I }, [field](const GAction&) {
+ difficulty_menu->add_action(GAction::create("Intermediate", { Mod_Ctrl, Key_I }, [field](const GAction&) {
  field->set_field_size(16, 16, 40);
  }));
- game_menu->add_action(GAction::create("Expert", { Mod_Ctrl, Key_E }, [field](const GAction&) {
+ difficulty_menu->add_action(GAction::create("Expert", { Mod_Ctrl, Key_E }, [field](const GAction&) {
  field->set_field_size(16, 30, 99);
  }));
- game_menu->add_action(GAction::create("Madwoman", { Mod_Ctrl, Key_M }, [field](const GAction&) {
+ difficulty_menu->add_action(GAction::create("Madwoman", { Mod_Ctrl, Key_M }, [field](const GAction&) {
  field->set_field_size(32, 60, 350);
  }));
- menubar->add_menu(move(game_menu));
+ menubar->add_menu(move(difficulty_menu));
 
  auto help_menu = make<GMenu>("Help");
  help_menu->add_action(GAction::create("About", [](const GAction&) {