[schema hooks] properly check for changes of schema properties avoid useless costly operation (such as full-text reindexing all entities of a type). Refactor inlined handling and fix a bug trying to reindex a final entity type on the way.

"""pre 3.6 bw compat"""
# pylint: disable-msg=W0614,W0401
from warnings import warn
warn('moved to cubicweb.mail', DeprecationWarning, stacklevel=2)
from cubicweb.mail import *