better captcha for EchoMF signup page

[River]

I get so many new forums signed up by spammers.

So, I fixed (with echos help) so they can't mess up the forum html to redirect to russian porn sites anymore but I woulf prefer if they couldn't create forums at all. My databases are getting full with these junk forums, it's a pain deleting them all.

So, better captcha, or something else to prevent these spammers from creating forums is my feature request.