constructor( options ) {
            options = options || {};

            this._maxCacheItemCount = options.maxImageCacheCount || $.DEFAULT_SETTINGS.maxImageCacheCount;
            this._tilesLoaded = [];
            this._zombiesLoaded = [];
            this._zombiesLoadedCount = 0;
            this._cachesLoaded = [];
            this._cachesLoadedCount = 0;
        }
@class TileCache
@memberof OpenSeadragon
@classdesc Stores all the tiles displayed in a {@link OpenSeadragon.Viewer}.
You generally won't have to interact with the TileCache directly.
@param {Object} options - Configuration for this TileCache.
@param {Number} [options.maxImageCacheCount] - See maxImageCacheCount in
{@link OpenSeadragon.Options} for details.