another attribute filtering thread

[Tom Zeller]

I started this new thread on attribute filtering because I was not
sure exactly where to fit my comments in to the existing threads.

I modified the "Anatomy" sections on the Attribute Filtering Engine
Architecture[1] page, first because of grammar, then to simplify.

Tomorrow I will likely chat with Rod about not porting the
MatchFunctor from v2 to v3. Both in code and schema it seems more of a
developer's shortcut than representing a domain object.

Where did the language "Policy Requirement Rule" come from ? I am
curious about terminology history.

As an aside, I would like the wiki, code+javadoc, and schema to align
clearly, if possible.

[1] https://wiki.shibboleth.net/confluence/display/IDP30/Attribute+Filtering+Engine