Bug 207268 Add visibility option for plot within axes
For chart with axes, we should make plot within axes invisible. Meantime, other plots, such as axes, legend and title, should be visible. This enhancement doesn't include UI change, and it is required for cross tab integration.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/AxesRenderer.java
{
			if ( ya.length % 2 == 1 )
			{
				rt = ya[ya.length / 2];
			}
			else
			{
				int x = ya.length / 2;
				rt = ( ya[x] + ya[x - 1] ) / 2;
			}
		}
		return above ? ( rt - height - gap ) : ( rt + gap );
	}
	/**
	 * Renders all marker ranges associated with all axes (base and orthogonal)
	 * in the plot Marker ranges are drawn immediately (not rendered as
	 * deferred) at an appropriate Z-order immediately after the plot background
	 * is drawn.
	 * 
	 * @param oaxa
	 *            An array containing all axes
	 * @param boPlotClientArea
	 *            The bounds of the actual client area
	 * 
	 * @throws RenderingException
	 */
	private final void renderMarkerRanges( OneAxis[] oaxa,
			Bounds boPlotClientArea ) throws ChartException
	{
		Axis ax;