protect: add support for the new templateeditor protection level

It's only available in the Template and Module namespaces, which is an
artificial restriction, but helps to reduce clutter in other namespaces
where it is really irrelevant.
morebits.css: gray out the label of disabled radios/checkboxes

Why not?
(I was surprised to learn that the :disabled pseudo-class is quite old -
even Firefox 1.0 knew about it...)