Massive cleanup

Cleanup includes : 
- Fix fake polymorphism in XmlBuilder ( i was sick of it, it was not maintainable, AND THERE IS NO SUCH THING IN PHP)
- Add sane Typehinting in Notice.php for XMLBuilder usages in closures, for better coding experience
- Fix the fixme in XmlBuilder when possible, sadly the code builds upon the "bug" so make the fix optional