D7714: Show dialog to ask when closing when more than tab open

[Albert Astals Cid]

aacid abandoned this revision.

REPOSITORY
  R223 Okular

REVISION DETAIL
  https://phabricator.kde.org/D7714

To: aacid, #okular, #kde_applications
Cc: alexeymin, ngraham, colomar, rkflx, #okular, aacid