Upgrade the default templates

Most of the templates are from the first versions of XWiki, and reflect the architecture of Dodo. This causes modern skins to override almost all of those templates, as they provide little reusability and extensibility.

Toucan shows that Albatross is stable enough to be considered a default base for skins, thus we should move most of the Albatross templates to the default templates directory, with a little cleanup/improvement work.