LinGui: increase max live preview duration to 240 seconds


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5260 b64f7644-9d1e-0410-96f1-a4d463321fa5
LinGui: increase max number of static previews to 60


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5261 b64f7644-9d1e-0410-96f1-a4d463321fa5