#334 dirent.h not part of delivery

[Falk Hähle]

After downloading the compilation fails due to missing <dirent.h> on Windows machines without an environment like Cygwin or MingW are installed. A good alternate implementation might be available in https://github.com/tronkko/dirent
So it should be checked if this OS dependency can be removed by providing a copy of the same.</dirent.h>