This adds a normalize_domain() method to osv.expression, which ir.rule calls
before combining expressions due to multiple rules or groups being applicable
to a certain user.
YAML tests are also added with a trivial unit test of normalize_domain() and
some additional tests for ir_rule in order to verify that unnormalized domains
are properly normalized before being combined by ir.rule.
bzr revid: odo@openerp.com-20110324111757-uwuoqvm3lxkipr08
444df6affa