Double-click on temporal sequences

https://med.inria.fr/redmine/issues/1624

Double-click on temporal sequences' thumbnails should take into account slice and TIME parameters, i.e we should visualize the selected slice at the selected time.

I first simplified what I did before with double-clicks, by putting medBrowserArea and medWorkspaceArea out of the signals transmission.

The time information is extracted from the thumbnail number and then transmitted to the medTimelineToolbox, to display the correct slice at the correct time.