Currently the assignment module ignores uploaded feedback files that sit within a subdirectory. Some of our clients have a common workflow which involves downloading all feedback files / submissions, extracting them into a directory, doing their marking and then right-clicking the directory and selecting an option to create a zip file, which places all of the files within a directory inside the zip.

This patch changes the code to accept files within any level of subfolder. Note however that there is potential for filename clashes. In the event of a clash, only one of the files will be uploaded as feedback, since the directory structure is not replicated to the feedback file area.