Anchor the popup to the top of the icon
Roy G. Biv
Don't render feature with all countries

The feature with undefined id is a multi-polygon representing all countries.  Instead of rendering all multi-polygons with a lower z-index, we just avoid rendering this single feature.
Merge pull request #1666 from tschaub/topojson-tweak

Don't render feature with all countries.
Merge pull request #1665 from tschaub/roy-g-biv

Roy G. Biv.
Merge pull request #1663 from tschaub/popup

Fix popup anchor in icon example.
Add a style option for vector layers

This can be a single ol.style.Style, and array of styles, or a style function.
Add tests for vector layer
Use style option in vector layer examples

Providing a styleFunction option still works because the layer property is still named styleFunction.