All Notary contract witnesses in incomplete transaction (both main
and fallback) may either have invocation scripts pushing dummy signature
on stack or be empty, both ways are OK. Notary actor keeps main tx's
Notary witness empty and keeps fallback tx's Notary witness filled
with dummy signature.
Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>
calculatenetworkfee MUST calculate complete proper network fee, if we have
some extensions enabled and some attributes should be paid for that they're a
part of the equation too.
Notes for witnesses:
* [N sig + M multisig + K contract] combination is possible where N, M, K >=0.
* Each verification script should be properly filled in.
* Each invocation script should either be empty or contain exactly one
signature.
