Already implemented, but... / #1874

Most of this features are already implemented, but I disabled them, because the cluttered the interface and are probably not the best way to handle this task. I think what we need is a quick way to create a "wiki page"-task.

Some background:

1. Due the the user right model we cannot have items outside of projects. That keeps us from attaching items to persons, because we do not know, how to check visibility for them. (I am still looking for a solution of this problem).
2. Although there could be project-comments, why not create a new tasks? If we introduce a task category anyway (see task categories) it would provide the same functionality and much more. (e.g. you could turn it into a real task and assign it. You could book an effort on a telefon conference, etc.). I am not sure how to link it to a person though...