Events are caught for only 1 annotation element

[stockiNail]

Currently the plugin is managing the events for 1 annotation element at once.

When 2 or more annotations are defined and are overlapped, the plugin is getting the element with the following rules:

1. the nearest element (distance from center)
2. if distance is the same, the biggest one

In the codepen https://codepen.io/stockinail/pen/zYPYXQY we can see how the inner box annotation can not catch any event.

I think this could be changed, enabling the event hooks invocation for all elements affecting by an event.

[stockiNail]

The plugin is going to the implementation of interaction options in the plugin in order to enable the users to select how events can be managed when there are overlapped annotations. See #659