Made the class Javadoc of AbstractRegionQueryCache sane.
Gutted ApplicableRegionSet.
Might as well make ApplicableRegionSet implement Collection<Region>.
Made ApplicationRegionSet implement Collection<Region>, and made it keep the given list sorted.
Added Stereotypes for group support for flags/attributes.

They are not yet functional because they require some extra mechanics not yet written (access to factories and whatnot).
Cleanup Attribute Javadocs.
Revert "Removed parents from regions."

Removal of parents will make upgrading extremely difficult and so consider them pending for the itme being.

This reverts commit df54d4de91d0c5bd30d3421010b6a0248b0cf546.
Added StringAttr.

The name of the class could be better.