Merge plone.namedfile support from collective.dexteritydiff:

Thanks to Rafael Oliveira's (@rafaelbco)
Merge AsTextDiff and BoolDiff support from collective.dexteritydiff
Merge plone.app.textfield support from collective.dexteritydiff
Merge ChoiceField support from collective.dexteritydiff
Merge compound dexterity diff support from collective.dexteritydiff
Integrate merged dexterity support into installation