Autozoom: add a margin to ensure all markers are displayed

The autozoom currently sets the zoom so that all the points are within the area of the displayed map. But if there is a point located at the very top of the map, the marker extends above the top of the map and can't be seen.

Suggested solution is to add a margin around the points so the zoom is always set leaving enough room to show the markers.

So in gmap_marker.js replace:

obj.map.setCenter(obj.bounds.getCenter(),obj.map.getBoundsZoomLevel(obj.bounds));

with

      var SW = obj.bounds.getSouthWest();
      var NE = obj.bounds.getNorthEast();
      var height = NE.lat() - SW.lat();
      var width = NE.lng() - SW.lng();
      // Set a 5% margin for left, right, and bottom, but 10% margin for top as markers are tall and need extra space
      var marginBounds = new GLatLngBounds(new GLatLng(SW.lat() - 0.05*height, SW.lng() - 0.05*width), new GLatLng(NE.lat() + 0.10*height, NE.lng() + 0.05*width) );
      obj.map.setCenter(marginBounds.getCenter(),obj.map.getBoundsZoomLevel(marginBounds));