Ability to sort by % downloaded and date finished at the same time #16

It would be really convenient to sort by two tabs simultaneously. As for now, if you sort by % downloaded you get all the torrents that aren't finished at the top but everything after that is unsorted. If there was an option to firstly sort by % and secondly by completion date one would be able to see all the stuff that is still downloading + latest downloads that are of most interest for the user