rxpd integration against spam

[ct]

filter anything (content) through rxpd by some policies to be defined.
Notably (where moinmoin fails):

• new usernames when creating accounts
• their email

for content:

• the filename itself
• the changed content (for plaintext)

which rxpd lists are used for filtering are defined by group membership and policies later.

later on the rxpd might get uwiki integrated (as action) so that the rxpd lists are content in the wiki!

[ichthyo]

cleaning up some rarely used trac tags...