[Framework-Team] Diazo ZPT fragment support

[Martin Aspeli]

Guys,

I'd really like some FWT input on

 https://github.com/plone/plone.app.theming/pull/10

It's ready to merge, but there seems to be different opinions about merit:

* Laurence and I see it as an important way to solve a certain class
of problems, where Plone's markup isn't sufficient as a base to
deliver what the theme required, without having to resort to full-on
filesystem development.

 * Dylan is against the idea, believing most/all use cases can be
adequately solved in content space with a combination of existing
portlets, TinyMCE styles and add-on products

 * A number of people seem to be on the fence

I'd like to merge this before it bitrots, and I think the
implementation is sound. However, I think it needs some FWT discussion
and approval first.

Martin