Changes 0.9 -> 0.91
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-Fixed crasher that occurs when switching from an archive to a .Z or .gz and then back to another archive. This caused the workspace to exit.

-Fixed update bug. If you clicked on a .Z or .gz after some other archive, the old archive's list would be there.

(Thanks to Robert Love for finding those!)

-Added ability to extract (in-place only) gzip and UNIX compress files.