isolate all headers to ensure that none rely on inclusions from another (#60)

test/compile/decl_header.cpp

@@ -0,0 +1,24 @@
+/*
+ *             Copyright Andrey Semashev 2015.
+ * 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)
+ */
+/*!
+ * \file   decl_header.cpp
+ * \author Andrey Semashev
+ * \date   21.06.2015
+ *
+ * \brief  This file contains a test boilerplate for checking that every
+ *         public header is self-contained and does not have any missing
+ *         #includes.
+ */
+
+#define BOOST_PREDEF_TEST_INCLUDE_HEADER() <boost/predef/BOOST_PREDEF_TEST_HEADER>
+
+#include BOOST_PREDEF_TEST_INCLUDE_HEADER()
+
+int main(int, char*[])
+{
+    return 0;
+}