Add msg_notfound, msg_reject and CTransaction.id()

[Flowdalic]

also use b2lx instead of hexlify for python3 support.

[petertodd]

re: CTransaction.id(), did you see how the most recent version has a .GetHash() doing that? (similar to the Bitcoin Core codebase)

[jtimon]

maybe

            setattr(CTransaction, 'id', getattr(CTransaction, 'GetHash'))

for convenience?

[Flowdalic]

re: CTransaction.id(), did you see how the most recent version has a .GetHash() doing that?

Nope. Shall I rebase the branch and remove e2acaca?

[petertodd]

@Flowdalic Sure, and give me some feedback on how that syntax/naming works for you.

[Flowdalic]

@petertodd rebased and removed the "Add id()" commit.