Added Sequence and optional detection.

This is part of the larger `Meta` library.  Need to implement
tuple-for-each and more.

Meta/is_string.h

@@ -0,0 +1,34 @@
+static_assert( __cplusplus > 201700, "C++17 Required" );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+#include <type_traits>
+#include <string>
+
+namespace Alepha::Hydrogen::Meta
+{
+	inline namespace exports { inline namespace type_traits {} }
+
+	namespace detail::type_traits::is_string
+	{
+		inline namespace exports
+		{
+			template< typename T >
+			struct is_string : std::false_type {};
+
+			template< typename T, typename ... Args >
+			struct is_string< std::basic_string< T, Args... > > : std::true_type {};
+
+			template< typename T >
+			constexpr bool is_string_v= is_string< T >::value;
+		} 
+	}
+
+	namespace exports::type_traits
+	{
+		using namespace detail::type_traits::is_string::exports;
+	}
+}
+