Removed numeric (don't use iota anymore)

Also placed the include on the top of cpp file.
Need to look into directinput and xinput hooks.

overlay_experimental/steam_overlay.cpp

@@ -6,7 +6,7 @@
 #include <imgui.h>
 #include <impls/imgui_impl_win32.h>
 
-#include <numeric> // iota
+#include "../dll/dll.h"
 
 extern LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
@@ -301,8 +301,6 @@ void Steam_Overlay::OverlayProc( int width, int height )
     //ImGui::ShowDemoWindow();
 }
 
-#include "../dll/dll.h"
-
 void Steam_Overlay::RunCallbacks()
 {
     if (overlay_state_changed)