love.event.quit
Adds the quit event to the queue.

The quit event is a signal for the event handler to close LÖVE. It's possible to abort the exit process with the love.quit callback.
love.event.quit( exitstatus )
exitstatus (0) number The program exit status to use when closing the application.
love.event.quit( 'restart' )
'restart' string Tells the default love.run to exit and restart the game without relaunching the executable.