Bug 194371 Use page emitter framework to implement ppt emitter.
In order to keep consistent with pdf and postscript, ppt need to use page emitter framework.
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTEmitter.java
public void startPage( IPageContent page )
	{
		PageArea pageArea = (PageArea) page.getExtension( IContent.LAYOUT_EXTENSION );
		if ( pageArea != null )
		{
			pageArea.accept( render );
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.emitter.IContentEmitter#start(org.eclipse.birt.report.engine.content.IReportContent)
	 */
	public void start( IReportContent report )
	{
		render.start( report );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.emitter.IContentEmitter#end(org.eclipse.birt.report.engine.content.IReportContent)
	 */
	public void end( IReportContent report )
	{
		render.end( report );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.emitter.IContentEmitter#startAutoText(org.eclipse.birt.report.engine.content.IAutoTextContent)