The current implementation of Filesystem::exists allowed to check whether a file is present on the filesystem, without any kind of distinction on the file type, so it is blind about the fact that it can be a file, directory, symlink, socket, ...

The new (optional) second argument allows to specify whether we want to check against a specific file type. I used the standard Unix/POSIX file types definition (seehttps://en.wikipedia.org/wiki/Unix_file_types), and implemented regular/directory. Class constants were added to list/use the available file types.

The change is BC and didn't alter the default/previous behaviour. I already pushed a usage example in the associated documentation.