Linear, threaded and hybrid modes not in the docs

[Stadler]

A chatter just asked over at #vbfans about the linear, threaded and hybrid modes and I looked, if I could find it in the manual, but I couldn't find anything about that. Maybe this should be added.

Or am I just blind?

[Floris]

I could not find it either, I will try looking harder next week and otherwise work on adding it to the appendix, linking from here: http://www.vbulletin.com/docs/html/main/features_1 perhaps.