Issue: Faster Auto-Links

Auto-Links make up a significant portion of page generation time for articles, especially for long articles. [vault=Forbidden/Limited List]One long article[/vault] typically generates in 1.3 - 1.9 seconds.

Changed for the next build by significantly reducing the number of preg_replaces. Previously, there was 1 match attempt for every existing article in the current namespace. Now, there is only 1 match attempt, unless the total combined length of the existing titles exceeds the maximum accepted by PCRE, in which case additional attempts will be created from the overflow.

Since the max length for the subject (the text that may contain autolinks) is significantly higher, I find it very unlikely this will reach the maximum length accepted. While it's possible to add handling for this too, it seems that checking if we're approaching the limit requires us to approach PHP's limits, so it's best to ignore this -- if we have an article that long, it wouldn't be the autolinks that bring the server down.

The described change has reduced autolink matching time (the time taken to complete about 10 lines of PHP) by 30-70% for long articles (the change is negligible for very short articles and forum posts).