OL3-Cesium 1.9 release


I am pleased to announce version 1.9 of OL3-Cesium,
based on OL 3.10.1 and Cesium 1.14.

This version brings many new features and improvements:
- an experimental opt-in automatic render loop to drastically reduce resources
  used when idle (100% -> 2% on my machine), which is based on code from Kevin Ring;
- the possiblity to add Cesium datasources (like KML);
- the possibility to create several Cesium counterparts and synchronize groups;
- many bug fixes.

In addition, support for layer saturation, gamma and hue was removed from OpenLayers3 so
we removed it from OL3-Cesium.

Thank you to all contributors of OL3, Cesium and OL3-Cesium for making this
release possible.