Add a total-order shim header.

Mathematical purism.

TotalOrder.h

@@ -0,0 +1,27 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <compare>
+
+#include "Concepts.h"
+
+namespace Alepha::inline Cavorite  ::detail::  total_order
+{
+	inline namespace exports
+	{
+		using TotalOrder= std::strong_ordering;
+
+		template< typename T >
+		concept TotalOrderable=
+		requires( const T &lhs, const T &rhs )
+		{
+			{ lhs <=> rhs } -> SameAs< TotalOrder >;
+		};
+	}
+}
+
+namespace Alepha::Cavorite::inline exports::inline total_order
+{
+	using namespace detail::total_order::exports;
+}