Add a bunch of TMP support.

I'm still on the fence about going full `constexpr` functions
for meta-code.  Overall, I think there's potential here.  I'm
not aiming to replicate what `boost::mpl` or `boost::hana` do
though.  This is more of an internal support mechanism for
Alepha code.  As-needed I'll implement things.

Meta/type_value.h

@@ -0,0 +1,45 @@
+static_assert( __cplusplus > 2017, "C++17 Required" );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+namespace Alepha::Hydrogen::Meta
+{
+	inline namespace exports { inline namespace type_value_wrapper {} }
+
+	namespace detail::type_value_wrapper
+	{
+		inline namespace exports
+		{
+			template< typename >
+			struct type_value {};
+
+			template< typename Lhs, typename Rhs >
+			constexpr bool
+			operator == ( type_value< Lhs >, type_value< Rhs > )
+			{
+				return false;
+			}
+
+			template< typename Value >
+			constexpr bool
+			operator == ( type_value< Value >, type_value< Value > )
+			{
+				return true;
+			}
+
+			template< typename T >
+			constexpr auto
+			make_value_type( T&& )
+			{
+				return type_value< std::decay_t< T > >{};
+			}
+		}
+	}
+
+	namespace exports::type_value_wrapper
+	{
+		using namespace detail::type_value_wrapper::exports;
+	}
+}