Create and select folders

[jdtsmith]

It would be useful to be able to create folders, and then select them in a single operation. With version 2.1.1, you can select existing folders with fileselect --select-only-directories, or you can allow the user to create new folders with filesave, but you can't both create a new folder and then select it to return. This would be useful for example for custom iPhoto export scripts, creating and returning a new folder to target the export.

[markhalliwell]

This is a relatively simple option to add. Should probably be --create-directories.