Merge pull request #734 from ventsin/develop-1.8

Fixed GCC compilation by adding <algorithm> to treebox.cpp

Author: qPCR4vir

source/gui/widgets/treebox.cpp

@@ -15,6 +15,7 @@
 #include <nana/gui/layout_utility.hpp>
 #include <nana/system/platform.hpp>
 #include <map>
+#include <algorithm>
 #include "../../detail/platform_abstraction.hpp"
 
 namespace nana