function SpriteSheetLoader(loadItem, preferXHR) {
		this.AbstractLoader_constructor(loadItem, preferXHR, createjs.Types.SPRITESHEET);

		// protected properties
		/**
		 * An internal queue which loads the SpriteSheet's images.
		 * @method _manifestQueue
		 * @type {LoadQueue}
		 * @private
		 */
		this._manifestQueue = null;
	}
A loader for EaselJS SpriteSheets. Images inside the spritesheet definition are loaded before the loader
completes. To load SpriteSheets using JSONP, specify a {{#crossLink "LoadItem/callback:property"}}{{/crossLink}}
as part of the {{#crossLink "LoadItem"}}{{/crossLink}}. Note that the {{#crossLink "JSONLoader"}}{{/crossLink}}
and {{#crossLink "JSONPLoader"}}{{/crossLink}} are higher priority loaders, so SpriteSheets <strong>must</strong>
set the {{#crossLink "LoadItem"}}{{/crossLink}} {{#crossLink "LoadItem/type:property"}}{{/crossLink}} property
to {{#crossLink "Types/SPRITESHEET:property"}}{{/crossLink}}.

The {{#crossLink "LoadItem"}}{{/crossLink}} {{#crossLink "LoadItem/crossOrigin:property"}}{{/crossLink}} as well
as the {{#crossLink "LoadQueue's"}}{{/crossLink}} `basePath` argument and {{#crossLink "LoadQueue/_preferXHR"}}{{/crossLink}}
property supplied to the {{#crossLink "LoadQueue"}}{{/crossLink}} are passed on to the sub-manifest that loads
the SpriteSheet images.

Note that the SpriteSheet JSON does not respect the {{#crossLink "LoadQueue/_preferXHR:property"}}{{/crossLink}}
property, which should instead be determined by the presence of a {{#crossLink "LoadItem/callback:property"}}{{/crossLink}}
property on the SpriteSheet load item. This is because the JSON loaded will have a different format depending on
if it is loaded as JSON, so just changing `preferXHR` is not enough to change how it is loaded.
@class SpriteSheetLoader
@param {LoadItem|Object} loadItem
@extends AbstractLoader
@constructor