Allow Viewing (and editing) of queue during downloading

[thatrobotdev]

It would be really nice if the queue wasn't locked while comics were downloading so that you can view what's next in the queue, and what's already been completed if it's really long.

Being able to modify the queue would also be neat so you could add new comics if you forget one before you hit start, or you can delete ones you no longer want to download/re-order comics in the order you want to download.

[pzkt]

This is a good idea and might get added in the refactored version of kea.