Option to add more operations to the queue

[robvh]

When doing copy or move, you can add multiple operations to the queue (f2)
Would be great if other operations (like packing/unpacking and deleting) could also be queued
Especially packing can often take long, and it would be great to queue them and walk away and look later

Also the queue handling itself could use a bit of a fresh-up
The list feels a bit Windows 95