Update some basic statistics.
'member' statistic updates the latest member, the total member
count, and the number of unapproved members.
'member' also only counts approved members when approval is on, but
is much more efficient with it off.
'message' changes the total number of messages, and the
highest message id by id_msg - which can be parameters 1 and 2,
respectively.
'topic' updates the total number of topics, or if parameter1 is true
simply increments them.
'subject' updates the log_search_subjects in the event of a topic being
moved, removed or split. parameter1 is the topicid, parameter2 is the new subject
'postgroups' case updates those members who match condition's
post-based membergroups in the database (restricted by parameter1).