Add stopEvent option in ol.OverlayOptions typedef
Add new container which don't stop event propagation

and allow overlays to optionnally stop event propagation
Adjust event propagation for overlay example
Adjust event propagation for popup example
Add controls to ol-overlaycontainer-stopevent

so that events won't be propagated to the map when interacting with a control
Merge pull request #1120 from bbinet/overlay-stop-events

Configurable event propagation for overlays