Move focus_ position update into handleMapBrowserEvent

Otherwise, the position is only updated on keyboard or mouse wheel events.
Follow-up improvements for #897

* Interaction is no goog.Disposable any more.
* Permanent cleanup during selection instead of disposeInternal.
* Moved selectionLayers creation outside feature loop.
* Maintain selectedFeatures and unselectedFeatures only for
  layers that have a setRenderIntent method.
Limit feature exports
Use ol.Coordinate instead of ol.geom.Vertex
Rename ol.geom.VertexArray to ol.CoordinateArray
Add missing provide and require for ol.geom
Remove map from control options
Don't export ol.control.Control.prototype.setMap
instanceof check to avoid ducktyping
Do not delete from oldFeatureMap
Add extra requires (see #958)
Update ZoomSlider example in docs
Call addControl instead of passing map to control
Call setMap instead of passing map to control
Exporting setMap so it is documented for custom controls
Export ol.Collection#getArray
Remove examples from control api docs

[ci skip]
Merge pull request #959 from probins/controlexamples

Out-of-date examples in control api docs
Add overlay-related methods to ol.Map
Remove map from OverlayOptions