Fixed compilation with gcc 4.7

Global.h

@@ -100,6 +100,7 @@ static_assert(sizeof(bool) == 1, "Bool needs to be 1 byte in size.");
 #include <boost/date_time/posix_time/posix_time_io.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/format.hpp>
+#include <boost/functional/hash.hpp>
 #include <boost/lexical_cast.hpp>
 #include <boost/logic/tribool.hpp>
 #include <boost/optional.hpp>