Add simple term blacklist functionality

One of the tiny, but impactful, features of the Mollom module (which will no longer be with us in a year or so) is it's simple blacklisting functionality. On many of my sites, where Honeypot and/or Mollom still take a beating and let through large numbers of human-powered spam, the Mollom term blacklist functionality has squashed about 90% of the common human spam I get. Here's the configuration for one of my sites that gets slammed the hardest:

Consider one fun spam comment I'd get 4x daily for a few months—the author was always "XRumerTest" and the contents were always "Hello. And bye."

After I added xrumertest to the blacklist, I never got another one of those comments again.

Obviously, content blacklists can be pretty bad for the UX, if you're not specific enough. If you blacklist the wrong terms (e.g. shorter words that could make up larger words in valid posts), then you can frustrate your users.

But used surgically, the blacklist is immensely helpful.

Therefore, my proposal:

• Honeypot adds a new configuration page/tab, titled 'Blacklist'.
• The Blacklist page is just a list of 'Blacklist values'.
• The user can add or delete (maybe edit too if it's simple enough) a blacklist value.
• Honeypot scans all fields in any form for which the new blacklist protection is applied, and checks for the term.
• If the term is found, the submission is rejected with a generic message like "This form submission was rejected due to spam protection filters... [something]." (Don't know exactly what to make this message say for decent UX).