With the fixes to `v_transactions` and `v_tx_outputs`, there are
several more data fields that may have no data (for rows corresponding
to purely-transparent transactions); their fields are made nullable.
* [#1170] Regular transaction flow emitting
Although zcash/librustzcash#918 will provide information on when to trigger transaction polling, this partly solves the issue as well
* Update changelog
Honza Rychnovský
Jack Grigg