Update bundled OpenLayers to a more recent version

[jqnatividad]

The bundled version is 4.2, which was released Jun 12, 2017.

Has the team considered at least updating to the latest 4.x release (4.6.5), which has the Vector image render mode, which gives a big performance boost?

Try out the image vector render here - https://openlayers.org/en/latest/examples/drag-and-drop-image-vector.html