function ManifestLoader(loadItem, preferXHR) {
		this.AbstractLoader_constructor(loadItem, preferXHR, createjs.Types.MANIFEST);

	// Public Properties
		/**
		 * An array of the plugins registered using {{#crossLink "LoadQueue/installPlugin"}}{{/crossLink}},
		 * used to pass plugins to new LoadQueues that may be created.
		 * @property _plugins
		 * @type {Array}
		 * @private
		 * @since 0.6.1
		 */
		this.plugins = null;


	// Protected Properties
		/**
		 * An internal {{#crossLink "LoadQueue"}}{{/crossLink}} that loads the contents of the manifest.
		 * @property _manifestQueue
		 * @type {LoadQueue}
		 * @private
		 */
		this._manifestQueue = null;
	}
A loader for JSON manifests. Items inside the manifest are loaded before the loader completes. To load manifests
using JSONP, specify a {{#crossLink "LoadItem/callback:property"}}{{/crossLink}} as part of the
{{#crossLink "LoadItem"}}{{/crossLink}}.

The list of files in the manifest must be defined on the top-level JSON object in a `manifest` property. This
example shows a sample manifest definition, as well as how to to include a sub-manifest.

		{
			"path": "assets/",
	 	    "manifest": [
				"image.png",
				{"src": "image2.png", "id":"image2"},
				{"src": "sub-manifest.json", "type":"manifest", "callback":"jsonCallback"}
	 	    ]
	 	}

When a ManifestLoader has completed loading, the parent loader (usually a {{#crossLink "LoadQueue"}}{{/crossLink}},
but could also be another ManifestLoader) will inherit all the loaded items, so you can access them directly.

Note that the {{#crossLink "JSONLoader"}}{{/crossLink}} and {{#crossLink "JSONPLoader"}}{{/crossLink}} are
higher priority loaders, so manifests <strong>must</strong> set the {{#crossLink "LoadItem"}}{{/crossLink}}
{{#crossLink "LoadItem/type:property"}}{{/crossLink}} property to {{#crossLink "Types/MANIFEST:property"}}{{/crossLink}}.

Additionally, some browsers require the server to serve a JavaScript mime-type for JSONP, so it may not work in
some conditions.
@class ManifestLoader
@param {LoadItem|Object} loadItem
@extends AbstractLoader
@constructor