[selectors] fix is_instance bug w/ parent classes. Also slight performance enhancements by changing what's returned by vreg['etypes'].parent_classes method (dedicated for this usage...) and removing no more necessary methods

# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s repository side views, usually for notification"""