Event handling improvements

[bhousel]

Related improvements involving the event handlers.

• Add zoomstart / zoom / zoomend events Add zoomstart / zoom / zoomend events #1958
• Propagate eventData to all event receivers all user-initiated events should include originalEvent #1975

[mourner]

Is there a reason to pack independent changes into one PR? It's easier to review small focused PRs and it's nice to be able to merge independently (e.g. in case one change is ready to merge while the other drags for a week).

[bhousel]

Is there a reason to pack independent changes into one PR? It's easier to review small focused PRs and it's nice to be able to merge independently (e.g. in case one change is ready to merge while the other drags for a week).

When issues are related I like to keep them together on a single feature branch to preserve the commit order and avoid merge conflicts. But I can break it up into different PRs, that's fine too.

[bhousel]

merged!