The big NULL replacement party part 5.

Right. ' = NULL' would get a lot of these.

src/ScreenMiniMenu.cpp

@@ -27,7 +27,7 @@ void FinishedLoadingScreen() {}
 // Settings:
 namespace
 {
-	const MenuDef* g_pMenuDef = NULL;
+	const MenuDef* g_pMenuDef = nullptr;
 	ScreenMessage g_SendOnOK;
 	ScreenMessage g_SendOnCancel;
 };
@@ -64,7 +64,7 @@ void ScreenMiniMenu::BeginScreen()
 	LoadMenu( g_pMenuDef );
 	m_SMSendOnOK = g_SendOnOK;
 	m_SMSendOnCancel = g_SendOnCancel;
-	g_pMenuDef = NULL;
+	g_pMenuDef = nullptr;
 
 	ScreenOptions::BeginScreen();