Bug 194549 Memory leak in chart device renderers
After memory analysis for Chart code, it indicates java.awt.Font objects are not garbage collected. Investigating the renderer code, Graphics2D objects in IDisplayServer and IDeviceRenderer are not disposed after chart rendering finished. Need to invoke IDeviceRenderer.dispose() after ChartReportItemPresentationImpl being finished, and dispose all required resources in that method, including IDisplayServer and anything else.
chart/org.eclipse.birt.chart.device.extension/src/org/eclipse/birt/chart/device/swing/SwingRendererImpl.java
loa[0] = LocationImpl.create( bo.getLeft( ), bo.getTop( ) );
			loa[1] = LocationImpl.create( bo.getLeft( ), bo.getTop( )
					+ bo.getHeight( ) );
			loa[2] = LocationImpl.create( bo.getLeft( ) + bo.getWidth( ),
					bo.getTop( ) + bo.getHeight( ) );
			loa[3] = LocationImpl.create( bo.getLeft( ) + bo.getWidth( ),
					bo.getTop( ) );
			return new ShapedAction( iev.getStructureSource( ), loa, clipping );
		}
		assert false;
		return null;
	}
	/**
	 * Reusable 'strokes' for rendering lines may be obtained from here
	 * 
	 * @param ls
	 * @return
	 */
	public final Stroke getCachedStroke( LineAttributes lia )
	{
		if ( lia == null )
			return null;
		Stroke s = (Stroke) _htLineStyles.get( lia );
		if ( s == null )
		{
			BasicStroke bs = null;
			if ( lia.getStyle( ).getValue( ) == LineStyle.DASHED )
			{
				float[] faStyle = new float[]{
						6.0f, 4.0f