Add hex/unhex algorithms suggested by Olaf

[SVN r77138]

test/hex_fail1.cpp

@@ -0,0 +1,25 @@
+/* 
+   Copyright (c) Marshall Clow 2011-2012.
+
+   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)
+
+    For more information, see http://www.boost.org
+*/
+
+#include <boost/config.hpp>
+#include <boost/algorithm/hex.hpp>
+#include <boost/test/included/test_exec_monitor.hpp>
+
+#include <string>
+#include <iostream>
+#include <vector>
+
+//	should not compile: vector is not an integral type
+int test_main( int , char* [] )
+{
+  std::vector<float> v;
+  std::string out;
+  boost::algorithm::unhex ( out, std::back_inserter(v));
+  return 0;
+}