Fix compiling on Windows with Visual Studio

src/client/imagefilters.cpp

@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <cmath>
 #include <cassert>
 #include <vector>
+#include <algorithm>
 
 // Simple 2D bitmap class with just the functionality needed here
 class Bitmap {

src/filesys.cpp

@@ -45,6 +45,7 @@ namespace fs
 #include <windows.h>
 #include <shlwapi.h>
 #include <io.h>
+#include <direct.h>
 
 std::vector<DirListNode> GetDirListing(const std::string &pathstring)
 {