Improve choice of window when a new tab is requested by kfmclient
requested to merge stefanocrocco/konqueror:improve-window-choice-when-opening-externally into master
Previously, the new tab was always created in the oldest window in the current desktop. Now, instead, the tab is created in the window which was last used. Besides, the window must not only be in the current desktop, but also in the current activity.