Refactoring: SproutNote member variable value moved to BaseNote.

All notes have a value, so the member variable has been moved to the
base class, and direct member access has been replaced with a getter.

src/wallet/asyncrpcoperation_sendmany.cpp

@@ -968,7 +968,7 @@ UniValue AsyncRPCOperation_sendmany::perform_joinsplit(
             getId(),
             tx_.vjoinsplit.size(),
             FormatMoney(info.vpub_old), FormatMoney(info.vpub_new),
-            FormatMoney(info.vjsin[0].note.value), FormatMoney(info.vjsin[1].note.value),
+            FormatMoney(info.vjsin[0].note.value()), FormatMoney(info.vjsin[1].note.value()),
             FormatMoney(info.vjsout[0].value), FormatMoney(info.vjsout[1].value)
             );