Problem with PG forum fixed

[markc]

I got a report 'Spark that forum 'guests' (someone who's just
looking, but is not actually logged in as a registered
forum user) were able to post messages in this PG forum.

Turns out that I'd neglected to set the perms for posting/replying
correctly.

Now this forum is like all the others : 'guests' can look, but they
can't create topics, reply, send personal messages, etc.

Sorry about the glitch!