[dataimport] remove implicit commits from MassiveObjectStore Let the user decide when to commit the transaction.

[dataimport] drop extra indirection through MassiveObjectStore._initialized dict We already have self.__dict__, no need to add another one for a static set of keys.

[dataimport] remove remaining references to dataio from MassiveObjectStore In particular, rename metadata tables to live in the ^cw.* namespace.

[dataimport] rename logger from dataio.massiveimport to dataimport.massive_store

[dataimport] remove commit_at_flush parameter from MassiveObjectStore WARNING: the default value was True, but flush() now never commits.

[dataimport] remove autoflush_metadata from MassiveObjectStore parameters Hopefully not needed.

[dataimport] remove uri_param_name from MassiveObjectStore parameters It doesn't belong here.

[dataimport] turn iid_maxsize into a class attribute

[dataimport] turn eids_seq_{start,range} into class attributes Only the master-mode store will actually use eids_seq_start to reset the eid sequence.

[dataimport] remove replace_sep parameter from massive store It is unused since changeset efbbf1e93a04 "[dataimport] Properly escape strings sent to COPY FROM"