Add ol.geom.Point#closestPointXY
Add ol.geom.LineString#closestPointXY
Add ol.geom.LinearRing#closestPointXY
Add ol.geom.Polygon#closestPointXY
Add ol.geom.MultiPoint#closestPointXY
Add ol.geom.MultiLineString#closestPointXY
Add ol.geom.MultiPolygon#closestPointXY
Add ol.source.Vector#getClosestFeatureToCoordinate
Have some fun in the complex-geometry example
Add snapping to synthetic points example (to be removed)