Expand test isolation to cover all global state, include default map functionality inspired by experimental.catalogqueryplan

Prevent ZopeTestCase to load any ZCML as a side-effect of calling Zope2.app(). Loading ZCML has to be deferred to layer setup time.

Sort indexes according to ILimitedResultIndex support. Indexes without the support are queried first, so the indexes supporting the feature already get a limited result set.

Make the tests a bit faster, there's really no difference between 100 and 1000 catalog entries. Testing really large numbers would be a different and interesting story.