[dataimport/test] update call to ucsvreader Silences warning: [3.20] 'separator' kwarg is deprecated, use 'delimiter' instead

[dataimport] remove deprecated methods from massive store This code is new in cubicweb, no reason for it to carry deprecated stuff from the start.

[dataimport/test] use store.finish instead of deprecated store.cleanup

[dataimport] drop no more used parameter on massive store

[dataimport] methods that modify in-place shouldn't return value Also mark those methods private and drop some useless comments in passing. Related to #5414760

[dataimport] implement new store API on massive store and deprecate the old one. Related to #5414760

[dataimport] .finish method was missing from (NoHook)RQLObjectStore

[massive store] identity_relation should not be considered, is_relation seems missing The "identity_relation" table should not even exist.

[dataimport/test] use the right assert methods instead of assertTrue with a comparison

[dataimport] import range from six.moves

[dataimport/test] feed binary data to ucsvreader

[dataimport/test] fix broken comparison We want to compare two ints, not an int and a db row

[dataimport] dict.iteritems() → dict.items()

[dataimport] use next builtin instead of next method on iterators