[querier] introduce RepeatList class, used to optimize size of data returned for result set description When rql query has no ambiguity, we used to return the same description * N where N is the size of the result set. Returning RepeatList class avoid that multiplication. According to quick benchmark this improve performance for result set whose size is ~ > 50, has very small penalty for rset < 50, and in any case improve the size of data to be transfered over the network through pyro connection.

# pylint: disable-msg=W0614,W0401
from warnings import warn
warn('moved to cubicweb.dataimport', DeprecationWarning, stacklevel=2)
from cubicweb.dataimport import *