KIND_SEP, SIGHASH_XXX, changes to verifying_machine api, p2sh.

KIND_SEP: new 'kind' for script elements, just for OP_CODESEPARATOR.
verifying_machine: take KEY constructor as an argument.
verify_sig: moved from TX.
get_ecdsa_hash: moved from TX, first whack at implementing SIGHASH_XXX.
verifying_machine_p2sh: pay to script-hash.
TX.verify: api changes.  check block timestamp to enable p2sh.
feed_block: pass block timestamp to verify, optionally disable yields.
include block timestamp in test lines.
verify the entire blockchain...

well... collect failure cases.