Improve stats parsing code.
Improve stats parsing code.

Also fixes stats not being properly saved/notified for interrupted archives.

shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui