ignore testing for nixio_fr
ignore testing for nixio_fr

* added a check to exclude testing IOs which have overridden the read_block() method and no longer accept "create_group_across_segment" as a valid argument

samuelgarcia/python-neo,NeuralEnsemble/python-neo,apdavison/python-neo,INM-6/python-neo,JuliaSprenger/python-neo