Added support for Translation Namespace autodetection

This is a function that I had running for years (at [www.inetsoftware.de](http://www.inetsoftware.de) ) but on a much older version of the DW core and plugin. I finally merged all the changes of the original plugin back in so that the auto detection is an add-on.

The auto detection is great for (like our case) one documentation wiki with all products, plugins and so on in different namespaces - all localized. So you can export (siteexporter) each namespace for a specific package with respective translations.

Additionally I added auto redirects (also optional) for translated pages. Once you switch the language it will stay for the session. We're using this on our website as well.

Finally there are some PHP Strict warnings I fixed.

Please note: Language Selection is now always being shown for the admin - I think that makes sense and it should maybe be configurable to also always show this to editors.