visiblePageDidChange behaviour

[caitlin-hutnyk]

The wiki seems to imply that the visiblePageDidChange event should occur when the active page (the one that takes up the majority of the screen) changes, but it seems to be occurring (for me on chrome and firefox, using diva 6.0.1) when the pages that are visible on screen changes.

If this is the intended behaviour it would be great for the wiki to be updated and for an event that occurs when the active page changes to be added.

[JRegimbal]

See #483.

[dchiller]

To do: Check whether this is solved with #483, and close depending on status.