Save game on window exit (#3339)

The game does not bother saving when the user exits the game via the window (or keybinds, etc). This fixes that.

Author: swagtoy

src/supertux/game_manager.cpp

@@ -38,6 +38,13 @@ GameManager::GameManager() :
 {
 }
 
+void
+GameManager::save()
+{
+  if (m_savegame)
+    m_savegame->save();
+}
+
 void
 GameManager::start_level(const World& world, const std::string& level_filename,
                          const std::optional<std::pair<std::string, Vector>>& start_pos)

src/supertux/game_manager.hpp

@@ -31,6 +31,8 @@ class GameManager final : public Currenton<GameManager>
 {
 public:
   GameManager();
+  
+  void save();
 
   bool start_worldmap(const World& world, const std::string& worldmap_filename = "",
                       const std::string& sector = "", const std::string& spawnpoint = "");

src/supertux/screen_manager.cpp

@@ -31,6 +31,7 @@
 #include "supertux/constants.hpp"
 #include "supertux/controller_hud.hpp"
 #include "supertux/debug.hpp"
+#include "supertux/game_manager.hpp"
 #include "supertux/game_session.hpp"
 #include "supertux/gameconfig.hpp"
 #include "supertux/globals.hpp"
@@ -183,6 +184,8 @@ ScreenManager::quit(std::unique_ptr<ScreenFade> screen_fade)
 {
   Integration::close_all();
 
+  GameManager::current()->save();
+
 #ifdef __EMSCRIPTEN__
   g_config->save();
 #endif