#5 layer cleans up on remove

added leaflet onRemove function to remove listeners and L.heat layer.
onRemove removes all map click handlers, I was having trouble removing them individually.  I think this could cause problems if an app had other handers listening.

example/example.js

@@ -30,20 +30,10 @@ function resetSolr()
 
     colorMap = colorMap.split(',');
 
-    if (solr)
-	{
-	    map.removeLayer(solr);
-	    map.off('moveend');
-	    solr._clearLayers();
-	    if (solr.heatmapLayer)
-		{
-		    // this code highlights the problem of L.SolrHeatmap creating L.Heat
-		    // perhaps L.SolrHeatmap needs to override remove layer
-		    map.removeLayer(solr.heatmapLayer);
-		    map.off("click");
-		}
 
-	}
+
+    if (solr)
+	map.removeLayer(solr);
 
     // if the doi field is present, we format it as an html link to the jstor document
     // first, a function to generate the html

leafletSolrHeatmap.js

@@ -35,6 +35,18 @@ L.SolrHeatmap = L.GeoJSON.extend({
 	    _this._getData();
  	},
 
+  onRemove: function(passedMap)
+  {
+      var _this = this;
+      passedMap.off('moveend');
+      _this._clearLayers();
+      if (_this.heatmapLayer)
+      {
+	  passedMap.removeLayer(_this.heatmapLayer);
+	  map.off("click"); // will this remove click handlers that it shouldn't
+      }
+  },
+
   _computeHeatmapObject: function(data) {
     var _this = this;
     _this.facetHeatmap = {},