MetacatUI

A first draft of the new map has been checked in.

The /#data DataCatalogView now retrieves the facets for all levels of geohashes, determines the geohash level to use based on map zoom level, and draws a circle on the map to represent the datasets in that geohash box.

The map clusters are Google Map Circle objects, which are given a radius based on the facet value - higher facet values are represented with higher radiuses. The number is drawn on the map using a custom Google Maps OverlayView object, which creates a div with the innerHTML as the facet value. This div is centered on it's corresponding circle position.

At the lowest map zoom level (whole world view), geohash level 2 is used. This seems to be the sweet spot for showing many clusters at once but not too many to keep it fast.

Currently, no individual markers are on the map. That is the next step.