Change the specifications of note decryption to return the note and memo, rather than a note plaintext. Generalize the specification of block chain scanning to support Orchard.
Change the specifications of note decryption to return the note and memo, rather than a note plaintext.
Generalize the specification of block chain scanning to support Orchard.

Signed-off-by: Daira Hopwood <cd7d43d5556a38ce626d53826fddc46adc597539@jacaranda.org>

zcash/zips,zcash/zips,zcash/zips,zcash/zips