Saving work in progress
Update
Support GZipped files
Merge remote-tracking branch 'origin/sql_autoindex' into sql_autoindex
Update
MusicBrainz: Exclude 1 track + recording that makes  batch-import loop
Remove type ":int" for column "number" for entity "track"
Supporting compressing rels_ files (gzip)
Offloading node ID/entity PK dict to disk (pickle) (needs cleaning up)