Portlet support: flexibility to configure the target component path with HstContainerPortlet

Currently, we need to configure define different sitemap item for different portlet views. For normal web applications, it is okay to force to define multiple sitemap items, but for portlet applications, it is too tedious to display different parts of a sitemap item in portlet windows.
So, I think it would be more convenient to allow configuring different target component paths with the same sitemap item for different portlet windows.