[rql rewrite] move some code from querier to rqlrewrite where it makes more sense. Also, make some minor cleanup/refactoring on the way and try to enhance docstrings. Relates to #3013535

#! /bin/sh -e
#

if [ "$1" = configure ]; then
  if which install-docs >/dev/null 2>&1; then
    install-docs -i /usr/share/doc-base/cubicweb-doc
  fi
fi


#DEBHELPER#

exit 0