add emitter

src/event/event.hpp

@@ -13,4 +13,11 @@ namespace VE
     std::any m_data;
     int m_id;
   };
+
+  struct emitter
+  {
+    virtual ~emitter();
+    virtual void on_event(event e) = 0;
+    virtual void on_attach() = 0;
+  };
 }