In order to provide popups for simple forms in themes other than sunburst,
I've moved the snippet of js that activates popup forms for logins,
confirmations and the contact form into Products.CMFPlone. That was formerly
in sunburst. I also added css support in plonetheme.classic for overlays.
As it stands with my last commits, migration from 3.x will install the popup
form activating js into the registry, but it will not be enabled. New
installs of plone 4 will have it enabled, with css support in classic and
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