using size_t like a half decent human being

include/gp/containers/buffer.hpp

@@ -48,7 +48,7 @@ namespace gp{
 		, end_elem{beg_ptr+sz}
 		{}
 
-		constexpr k">typename pointer_iterator<T>::difference_type size() const
+		constexpr n">size_t size() const
 		{
 			return end_elem - begin_elem;
 		}