False matches (wrong case) when making links

Migrated issue

Reported by: jhodgdon

In _filter_url_tips() for instance (and many other places I think), there is a link in the documentation that isn't right. (I've seen this in code too, it's not just documentation.)

The text is "URL", and it's linking to the url() function.

The reason is that the matching for making links is using MySQL, which is case insensitive. When we're looking for matches, once we get the query result, we should double-check that the string is an exact match before accepting it as a match.