Add an example for the new webgl vector layer

This example accomodates for hit detection whih is not functional yet.

examples/webgl-vector-layer.html

@@ -0,0 +1,10 @@
+---
+layout: example.html
+title: WebGL Vector Layer
+shortdesc: Example of a vector layer rendered using WebGL
+docs: >
+  The ecoregions are loaded from a GeoJSON file. Information about ecoregions is shown on hover and click.
+tags: "vector, geojson, webgl"
+---
+<div id="map" class="map"></div>
+<div id="info">&nbsp;</div>