Add confirmation dialog on close when video is exporting

[fotosav]

Amazing tool! :)

I suggest add confirmation dialog on window close when video is exporting: "Video is exporting (in queue). Quit anyway?" [OK/Cancel] It is especially important for 'Batch encoding'.

[Andrew Baldwin]

Should be fixed in git as suggested by aeb089d989a1688ac54e22812b233c755aa946bd Fix should be in 1.1.4 binary release