Add event/method to determine whether to open or not

[danb-humaan]

I propose adding an event during the open call that can be used to determine whether the modal should open. As the logic behind the event would be performed in the event itself, rather than in Modaal, so this would increase the filesize by only a fraction.

Ideally it should take either a boolean value, or a closure to be called.

I can tackle this later during the week, pending @danhumaan's thoughts.

[danhumaan]

Thanks mate, new version will be rolled out shortly.

[danhumaan]

Thanks mate, this has been rolled out in the latest release now!