The setStyle method accepts a single style, an array of styles, or a style function. The getStyle method returns what was set. Internally, we use the getStyleFunction method which always returns a function. When calling setStyle, a change event is dispatched (fixes#1671).
With symbolizer literals now being geometry type specific, we no
longer need the overhead to query the RTree separately for each
geometry type and render symbolizer groups by geometry type.
The geometry type index of the FeatureCache is no longer needed.
The filtering functionality of the FeatureCache's
getFeaturesObject method can be removed because it is no longer
used.
With this change, getFeaturesObjectForExtent may return null if
the source does not have data loaded for the provided extent.
A callback can be passed to getFeaturesObjectForExtent to get
notified when the requested data is available.
The canvas vector layer still has the (API candidate) `getFeatures` method that accepts an arbitrary expression (was filter). This, and the `getFeaturesObject` method under it are only used in the tests. The rendering code that was using filters is now calling `layer.getFeaturesObjectForExtent` with an explicit extent and optional geometry type.
The color names are more intuitive. And if we want to support pattern strokes or fills, we'll need additional proerties to represent other pattern properties.
