Support P2SH / BIP16

[JornC]

Script interpretation currently doesn't understand the BIP16's OP_HASH160 [20 bytes] OP_EQUAL output format, and so it doesn't show the embedded redeemscript in a spending input's scriptSig, nor does it show invalidity of an invalid P2SH transaction (but otherwise valid)

[Giszmo]

$20 from me for a fix. thumbs up if you want to bump the bounty with an equal amount.