A new namespace for Portals(so-called Wikiportal). Now namspace portals are put
on are different by project. On some ns:0 (de:), on some ns:4 and for example,
"Wikipedia:Wikportal:XX" is redundant. On the other hand, ns:0 is not a proper
place, since they are not articles of encyclopedia apparently. Polish Wikipedia
uses ns:0 too but they name those pages "Wikiportal:XX".
In my opinion it would be better to create a new namespace and put those pages
in a same namespace across the project.
See also: http://meta.wikimedia.org/wiki/Special_namespaces_for_portals_and_lists