Documentation-Branch v2

Working URLs for the sets.xml have been restored; the sets are complete and up to date now. The file works with the (trivial) oracle fix from my other branch.
The sets.xml can now be created on any Linux system with the script included in the pull request. It creates more entries as the Gatherer lists (like 15th Anniversary Promos), but that does not matter.
The LaTeX documentation aka usermanual contains all information from the dokuwiki.
The URL in the centos howto has been updated.