When signing an input, figure out what was requested for but was unable
to be found and store it in a SignatureData.
Return this information in SignPSBTInput.
Refactor the new CombinePSBT, FinalizePSBT, and FinalizeAndExtractPSBT
general-purpose functions out of the combinepsbt and finalizepsbt RPCs,
for use in the GUI code.
Remove the op== on PartiallySignedTransaction, which only checks that the
CTransactions are equal. Instead, check this directly in Merge, and return
false if the CTransactions are not equal (so the PSBTs cannot be merged.)
After refactoring general-purpose PSBT and transaction code out of RPC code,
for use in the GUI, it's no longer appropriate to throw exceptions. Instead we
now return bools for success, and take an output parameter for an error object.
We still use JSONRPCError() for the error objects, since only RPC callers
actually care about the error codes.
Move non-wallet PSBT code to src/psbt.{h,cpp}, and PSBT wallet code to
src/wallet/psbtwallet.{h,cpp}. This commit contains only code movement (and
adjustments to includes and Makefile.am.)
