/computer/*/doDelete should try harder to remove even a “zombie” Computer with no associated Node.

If unwrap returns null, we need to fall through to load to try it again.
(cherry picked from commit 04c87d8d)

Ensure that SortedList clones the underlying data list.
Without this changes to a clone also change the original list.
(cherry picked from commit 761c4379)

Ensure that SortedList clones the underlying data list.
Without this changes to a clone also change the original list.

Added uninstaller that removes *.jpi.

Thanks to newenigma for catching.