rev.87

1. Fix xss in bbcode.
2. Expand censorship to block spam. Added 'Censor words - limit' to the Options.
3. Strengthened form checks against automated registration/message posting.

Note 1: There is a high probability that browsers from 1990-2019 (and forks based on them) will not pass form checks.
Note 2: Set up security headers on your sites. Examples for Apache and nginx are here.