+ Added {extends} and {block} to handle template inheritance, read more about it at http://wiki.dwoo.org/index.php/TemplateInheritance
{extendsCheck} is just an helper plugin for {extends} and should not be called by users

git-svn-id: svn://dwoo.org/dwoo/trunk@22 0598d79b-80c4-4d41-97ba-ac86fbbd088b