Disable P2SH

[adamkrellenstein]

Right now v1 forces P2SH encoding, at least for MPMA transactions. Both v1 and v2 should default to multi-sig, since P2SH is unreliable (#2270 #1383). (It's also probably more expensive in many cases, because it uses multiple transactions.) All of this is a stopgap, given we're gonna be doing all encoding using witness data in the near future (cf. #1375).

[adamkrellenstein]

apparently this actually has something to do with memo, memo_in_hex, and the version of bitcoin core / python-bitcoinlib being used...

[adamkrellenstein]

So it turns out that our P2SH encoding no longer works with recent versions of Bitcoin Core. It was the default only when use_old_api=False was specified. This is causing loss of user funds. Here's the test demonstrating that: #2283

In addition, there were two other bugs in the P2SH implementation:

1. fee_per_kb is required for P2SH #2287
2. tx sanity check is broken when there is a destination #2288

Plus we also ran into: #2286

[ouziel-slama]

done here #2290