Added license header.

settable.hpp

@@ -1,3 +1,16 @@
+//! \file settable.hpp
+//! \brief C++ Library (header-only).
+
+//  settable.hpp  ------------------------------------------------------------//
+
+// 
+// Copyright Jens Luedicke 2010
+// 
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+//----------------------------------------------------------------------------// 
+
 #ifndef SETTABLE_HPP
 #define SETTABLE_HPP