Catalog changes:
  * Remove pg_shadow/pg_group
  * Add pg_authid and pg_auth_members
  * Add indexes for pg_authid/pg_auth_members
  * Add array_accum function for backwards compatible pg_group
  * Add views for pg_shadow/pg_group

ACL system changes:
  * Change AclId to Oid
  * Change all 'owner' types to Oid
  * Need to implement per-backend role-member cacheing 
  * Need to do multi-level role resolution when filling the cache
  * Implement use of the per-backend role-member cache in ACLs
  * Add hooks to update per-backend role-member cache on pg_auth_members changes
  * Change ownership checks to consider members of a role as owners
    for anything that role owns
  * Allow ownership change to role which role is a member of
  * Support 'grant <role> to <role>'
  * Support 'with admin option'
  * Support 'granted by'
  Fix grant role/revoke role grammar to match SQL spec 
    (remove 'ROLE' and fix reduce/reduce conflicts)
  Fix grant role/revoke role grammar wrt 'admin option'
    (currently gives syntax error when 'with admin option' is used)
  Verify 'with admin option' working correctly
  Check/prevent role circles/loops

On-Disk file format changes
  * Merge pg_authid and pg_auth_members into one file
  * Perform full role expansion in backend during file generation
  * Sort roles before writing pg_auth file
  * Support log replay (do not use indexes, etc)
  * Remove sorting from client startup

Parser/commands changes
  * Add CREATE ROLE mechanism
  * Change C functions to role-based
  * Fix CREATE ROLE to support all CREATE USER/CREATE GROUP options
  * Adjust CREATE USER/CREATE GROUP to use role-based C functions
  * ALTER ROLE changes (mimicing CREATE ROLE, etc)
  * RENAME ROLE
  * DROP ROLE
  * Warn that SYSID is no longer a valid option and to not depend on it
  * Add on additional options to create role which are now available
  * Implement better DROP ROLE mechanism (instead of seq scan pg_auth_members)
  * Adjust CREATE USER/CREATE GROUP to imply canlogin/nologin respectfully
  * Fix other parsers (ecpg, etc) based on updates to backend/parser.
  ? Distinguish 'create role' permissions from 'superuser'?

psql changes
  Modify \du, \dg to use new tables
  Add \dr, \dm
  ? Depreciate \du, \dg

Documentation
  Add documentation for CREATE ROLE/etc
  ? Depreciate CREATE USER/CREATE GROUP
  Document new system catalogs (pg_authid, pg_auth_members)

Regression tests
  Verify regression tests still pass