Spambot Protection added to NLSC Wiki

In an effort to curb the problem with spambots making unwelcome changes to our Wiki since opening it up to unregistered edits, I've added a CAPTCHA which must be filled out whenever an edit is made by an unregistered user or when a new account is registered. Registered users meanwhile will not have to enter the CAPTCHA while editing pages. I hope this will not prove to be intrusive or deter anyone from contributing to the Wiki as we want to allow unregistered edits with a minimum of fuss and keep as many pages as possible unlocked and open to public contributions, however we also need to protect our articles and discussion pages from the junk that spambots post.