This adds the following:
- unzip archives
- if dest dir already exists (typicaly update case),
unzips in a temp dir then swap dirs then delete
the old install. In case of error, the old archive
has not been lost.
- computes stats for download: percentage, speed, time left.
- compute percent for install, on top of progress bar.
The install code will need to move somewhere
out of the window. I think I'll put in the Archive
itself with the window just looping on all archives
and doing some progress bar bookeeping.
f555bd3bff