add (very) basic main menu

include/td/common/StateMachine.h

@@ -1,7 +1,7 @@
 #pragma once
 
-#include <memory>
 #include <cassert>
+#include <memory>
 
 namespace td {
 
@@ -15,6 +15,11 @@ class StateMachine {
 
 		virtual TReturn Update(TArgs... args) = 0;
 
+		template <typename T, typename... Args>
+		T* ChangeState(Args&&... args) {
+			return m_StateMachine.template ChangeState<T>(std::forward<Args>(args)...);
+		}
+
 	  protected:
 		TDerived& m_StateMachine;
 	};