Show all defined records

Rarely, 24 hour blocks will still contain undefined records.

These are infrequent enough to not impede overall analysis (you can use
mv.heap.def.filterAll(); dc.redrawAll() to confirm), but when loading in
multiple datasets, can have a substantial number of records occurring
before them.

This should become a non-issue again when the scrubber keeps track of state
outside of the logs being collated.