Layers and shared pointers and unittests

[Cyrille Berger]

> Well, that's only doable by making sure everything uses a script to
> checkin, one that first runs unsermake check, and then svn ci. I'm not sure
> how I'm going to be able to enforce that :-).
well we are nice people, if you tell us what to do we do it, you may have 
notice than since some time design talk are again held on mailing list :)
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--- Cyrille Berger ---