restart(): the `restart` and `ready` events had an arbitrary order of appearance (at least theoretically): the `ready` event now includes a `restarting` event data attribute to inform user code that the `ready` is part of a restart process, while the new `restart:before` event is fired *before* the restart process begins so that user code can save or otherwise process the old state of affairs before it is lost forever.
restart(): the `restart` and `ready` events had an arbitrary order of appearance (at least theoretically): the `ready` event now includes a `restarting` event data attribute to inform user code that the `ready` is part of a restart process, while the new `restart:before` event is fired *before* the restart process begins so that user code can save or otherwise process the old state of affairs before it is lost forever.

Do note that the `restart` event is now dead.

Also unquoted all event attributes: one coding style everywhere -- and one which has the minimal amount of quoted buggerit.

GerHobbelt/reveal.js,GerHobbelt/reveal.js,GerHobbelt/reveal.js