Fix issue #33 by adding a conditional code block for mingw platform

[xaedes]

Fix issue #33 by adding a conditional code block for mingw platform that calls the correct mkdir function.

The mkdir function provided by (admittedly my) mingw platform lacks the mode parameter. This part in the FileUtils.hpp file is conditionally compiled. When compiling in Visual Studio (defined(_MSC_VER)==true) another function_mkdir without the mode parameter is called. In Mingw the function is called mkdir.

[masamitsutech]

This pull request will be reviewed for the next stable release.

This pull request will be closed if the change is accepted and merged into the toolkit. If any issues are found, we will report those here to be resolved.