possibility to work on files during upload

[hpvd]

same reason and details like
possibility to work on already uploaded files #112
but during upload

One can already cancel uploads (that's great!)
but after that one has to

• re-find,
• re-select,
• edit and
• re-upload

the file.

=> maybe one can simply this for the user by letting him "edit" also "uploading files"
and in background a new copy of the file is made and edited and automatically started to upload?

[arturi]

Added to backlog, thank you!