Bug 199834 Enable access to IContent object in IReportItemPresentation layer
In IReportItemPresentation layer, the extended item may want to access properties from current IContent object, for example, bookmark, content style. So we need expose the content object in this layer.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/extension/IReportItemPresentation.java
/**
	 * sets the image formats that are supported for this output format. Formats
	 * are separated by semi-colon. For example, the argument could be
	 * JPG;PNG;BMP;SVG
	 * 
	 * @param supportedImageFormats
	 *            the image formats that the presentation engine could support.
	 */
	public abstract void setSupportedImageFormats( String supportedImageFormats );
	/**
	 * deserializes generation time state information about the extended item
	 * 
	 * @param istream
	 *            the input stream to deserialize generation time state from
	 */
	public void deserialize( InputStream istream );
	/**
	 * returns the output type, which could be IMAGE, TEXT, HTML TEXT, DRAWING,
	 * etc. For now, only Image is supported.
	 * 
	 * @param mimeType
	 *            an out parameter that returns the MIME type of the output
	 * @return output type, for now OUTPUT_AS_IMAGE only
	 */
	public int getOutputType( );
	/**
	 * processes the extended item in report presentation environment.
	 * 
	 * @param rowSets
	 *            rowSets an array of row sets that is passed to the extension