#270202: After disabling TAC when it's the only node_access module, the default node_access row wasn't replaced.

make update_5 destructive of old rows
don't allow role name passed to rule interface functions

which reduces code complexity and makes administration easier.
The admin interface for managing access rules has not been updated, so definitely don't try to run this branch yet.

_taxonomy_access_update_db(): Getting old_rids from table 'term_access_defaults' (instead of table 'term_access'), since we want to make 'term_access' table "sparse" in the future.

Adding more troubleshooting comments and uninstall section to README.txt. Adding note to install.txt

Adding warning message to check default permissions + clearing some of _taxonomy_access_update_db();

#http://drupal.org/node/146488 duplicate entry + bugfix in _taxonomy_access_update_db() to update term_access_defaults table correctly.