Fix from ORBLISH suggestion to stop any component that's not hover/clicked on in the mouse handler.

guecs.hpp

@@ -93,6 +93,7 @@ namespace guecs {
 
     void init(lel::Cell &cell);
     void run();
+    void stop();
     void step();
     shared_ptr<sf::Shader> checkout_ptr();
   };
@@ -100,6 +101,7 @@ namespace guecs {
   struct Sound {
     std::string on_click{"ui_click"};
     void play(bool hover);
+    void stop(bool hover);
   };
 
   struct Background {