Add ol.geom.Polygon#getLinearRingCount function
Document ol.geom.Polygon#getLinearRing function
Set inherited values
ol.layer.Vector.getSource return type specialisation.
Remove unnecessary type cast
Merge pull request #2651 from gberaudo/layer_vector_source_specialisation

ol.layer.Vector.getSource return type specialisation.
Add olx.layer.ImageOptions typedef
Set ol.layer.Image#getSource return type to ol.source.Image
Remove unnecessary type cast
Set ol.layer.Tile#getSource return type to ol.source.Tile
Remove unnecessary type cast
Merge pull request #2656 from fredj/image-layer-source-type

Set ol.layer.Image#getSource return type to ol.source.Image
Use the feature style if defined

Same behavior as ol.layer.Vector
Use a custom style for the position feature
Merge pull request #2676 from fredj/featureoverlay-style

ol.FeatureOverlay: use the feature style if defined
Add TextStyle offsets getters to API.

The other properties getters are in the API already.
Merge pull request #2677 from gberaudo/export_text_style_offsets

Add TextStyle offsets getters to API.
Mutable symbolizer properties for style functions

This change adds setters for symbolizer properties. In addition, it
introduces a mutable flag on all styles. By default, this is set to
true. ol.style.createStyleFunction sets it to false for all static
styles.

The new setters assert that the mutable flag is true, so whenever an
application tries to set a symbolizer property on a style that was
assigned to a vector layer or feature overlay, the assertion will fail.
Additional documentation
Merge pull request #2534 from fredj/polygon-api

Document ol.geom.Polygon#getLinearRing function