UploadField now behaves more consistently with other fields; It now correctly loads and stores posted form data in it's own field value as per convention. UploadField::setValue and UploadField::getValue now works as expected, and the form field itself will now correctly limit its form data to a top level $_POST[FieldName] key (with [Files] as a nested subkey) meaning that RequiredFields is now compatible with this field.
Cleanup of PHPDoc, and removed obsolete configuration from _config/uploadfield.yml
UploadField::getFileEditFields, UploadField::getFileEditValidator, UploadField::getThumbnailURLForFile, and UploadField::getFileEditActions first parameter is now mandatory
Removed the 'null' File field from UploadField.ss to be compatible with RequiredFields / field convention
Updated FormField with correct PHPDoc