WIP : CFD-144 log group activity

Modules to support logging activity in the message table for:
* create/edit/delete node content.
* create/edit/delete comments.
* activities about users and group membership.
I always try to avoid assigning variables in conditions (this is considered a bad practice).

Code inside a condition should be the condition.
In a condition you expect operators like ==, ===, !=, !==, < , ...
= looks like a bug… (its like the assignment was a typo and should have been == or ===.