Stateful object initialization

As discussed with Dylan, a try to get the write-up at http://dojo-toolkit.33424.n3.nabble.com/dojo-Stateful-constructor-chaining-tp4001006p4001158.html into the reference guide format.

Syntax untested yet (it's midnight), but a first review would be nice. Is this up to standards?

(CLA coming in the next few days).