[session] have a nice helper function to forward access to session
This allows a lighter and clearer code. This will also ease the addition of
deprecation warning in the future.
if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
ask_confirm=False):
rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
ask_confirm=False)