Bug 130495 Get rid of SessionHandleAdapter
Now, we use SessionHandleAdapter to keep current active report deisng. That's a bad practive for editor swith and rebuild will cuase lots of problmes. Need find way to replace it.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/core/model/SessionHandleAdapter.java
* Create report design instance
	 * 
	 * @return created report design instance
	 */
	public ModuleHandle creatReportDesign( )
	{
		return getSessionHandle( ).createDesign( );
	}
	/**
	 * @return wrapped report design handle.
	 */
	public ModuleHandle getReportDesignHandle( )
	{
		if ( designHandleAdapter != null )
		{
			return designHandleAdapter.getModuleHandle( );
		}
		return null;
	}
	/**
	 * Sets report design.
	 * 
	 * @param handle
	 *            the model
	 */
	public void setReportDesignHandle( ModuleHandle handle )
	{
		if(designHandleAdapter!=null)
		{
			designHandleAdapter.setReportDesignHandle( handle );