#138 More field in online table for module extra info

[D.J.]

Add one field, for say "online_extra" or "module_extra"
as TEXT or VARCHAR(255), so that necessary info could
also be stored, like the forum board or the topic that
a user is browsing.

Currently the feature in NewBB 2 is done with a very
ugly and unefficient solution by adding extra table and
extra treatment.