Pushed subtitle offset default from +-10s to +-60s

While this is perfectly doable for anyone via advancedsettings.xml I think it might be valid to make the default a bit larger than 10s. What I've seen when used offset is that either its syncing alright and then +-10s is fine to make it ok for the entire video, or its drifting (not sure why it drifts but) and then 10s is far from enough.