More options for wordfilters

[Eggbertx]

Gochan's wordfilter implementation should be changed so that wordefilters can do any of the following:

• [x] Change the matching text to a given string (already supported)
• [ ] Reject the post
• [ ] Reject the post and ban the poster IP with a given reason and length
• [ ] Moderators should also be able to add wordfilters (currently only admins can)
• [ ] Log the matching post but don't reject or change it