Do not make copies of working copy files when dragging to other applications

Therefore, the users may edit the working copy files instead of just viewing temporary files

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Create temporary directory for dragging files on demand

No need to create if all of them are files of working copy

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>