URLs and redirects from old wiki URLs

[Fernando-A-Rocha]

We gotta figure out a definitive scheme of URLs

Right now, I've determined the following:

• /reference/: folder containing all pages that define functionality of MTA scripting/server/client stuff
• /articles/: fan-made or "official" articles that are additional and don't define anything, they are usually guides/tutorials

I've put functions in e.g. /reference/setElementPosition and ID_Lists in /reference/ID_Lists

The 404 page contains some JS code to perform redirects of URLs to /reference/[...] and /articles/[...] if they are missing that suffix,
which makes URLs like /setElementPosition work, redirecting to /reference/setElementPosition

This is debatable, so I'm open for suggestions.

cc @FileEX