Moved nullopt monostate out of optional

include/gp/functional/monostates.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace gp{
+	struct nullopt_t final{};
+
+	constexpr nullopt_t nullopt;
+}

include/gp/functional/optional.hpp

@@ -3,6 +3,7 @@
 #include "gp_config.hpp"
 
 #include "gp/functional/bind_front.hpp"
+#include "gp/functional/monostates.hpp"
 #include "gp/algorithms/move.hpp"
 #include "gp/exception.hpp"
 
@@ -10,9 +11,6 @@
 #include <new>
 
 namespace gp{
-	struct nullopt_t final{};
-
-	constexpr nullopt_t nullopt;
 
 	template<typename T>
 	class optional final{