fix for #1172 (ReferenceStrip not freeing resources)
fix for #1172 (ReferenceStrip not freeing resources)

LarissaSmith/openseadragon,LarissaSmith/openseadragon,seanich/openseadragon,seanich/openseadragon,openseadragon/openseadragon,openseadragon/openseadragon