{sign|verify}message replacement

In this conversation, the discussion is about signing a script and the time conditions under which it may be spent. The participants suggest assuming sufficient time/height on CLTV/CSV checks when there's no input. They also mention including an optional nLockTime in the proof container which defaults to 0, and nSequence that defaults to 0xFFFF. The default SIGHASH_ALL is suggested for simplicity unless there's a good reason to tweak it. Finally, it is recommended to append a byte to the end of the signature to pass encoding checks, but it could be a 0x00 byte as it's not actually a sighash flag.