Add an option to make the quest cancel on logout

[WataLaker37821]

Here is the plan: When player logs out quest should be cancelled,

Also if possible: please consider a feature to make a quest for a one player at a time (so other players couldnt accept it if player didnt cancel / complete it).

And if you could sometime in a future: please consider adding a time limited quests with a timer in the scoreboard, it will be a good addition.

Sorry if this is too much, but i hope you will like these features ideas, your plugin is easiest and more useful than other quest plugins i tried, so i believe in it's potential!