Fix #160
Fix #160

If we are added to the map, then removed, then a marker is removed from us. Previously that marker wouldn't be removed, now it is when we get re-added to the map.

meboban/Leaflet.markercluster,cyrilchaponeverysens/Leaflet.markercluster,tobias-johansson/Leaflet.markercluster,zoutepopcorn/Leaflet.markercluster,604557209/byzgf,VincentDS/Leaflet.markercluster,nerik/Leaflet.markercluster,604557209/byzgf,Leaflet/Leaflet.markercluster,ghybs/Leaflet.markercluster,zverev/Leaflet.markercluster,paulserraino/leaflet-geojson-cluster,hoganmaps/Leaflet.markercluster,paulserraino/leaflet-geojson-cluster,alex2wong/Leaflet.markercluster,VincentDS/Leaflet.markercluster,Intermaps/Leaflet.markercluster,hoganmaps/Leaflet.markercluster,meboban/Leaflet.markercluster,zoutepopcorn/Leaflet.markercluster,nerik/Leaflet.markercluster,zverev/Leaflet.markercluster,Chuck8080/web-maps-markercluster,lrpauley/Leaflet.markercluster,Intermaps/Leaflet.markercluster,MazeMap/Leaflet.markercluster,frenomus/Leaflet.markercluster,Leaflet/Leaflet.markercluster,MazeMap/Leaflet.markercluster,lrpauley/Leaflet.markercluster,ghybs/Leaflet.markercluster,cyrilchaponeverysens/Leaflet.markercluster,radnor/Leaflet.markercluster,radnor/Leaflet.markercluster,mr47/Leaflet.markercluster,frenomus/Leaflet.markercluster,mr47/Leaflet.markercluster,alex2wong/Leaflet.markercluster,tobias-johansson/Leaflet.markercluster