bitcoin: add weight calculation helpers.

These are pulled from wallet/wallet.c, with the fix now that we grind sigs.

This reduces the fees we pay slightly, as you can see in the coinmoves changes.

I now print out all the coin moves in suitable format before we match:
you only see this if the test fails, but it's really helpful.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/utils.py

@@ -1,6 +1,7 @@
 from pyln.testing.utils import TEST_NETWORK, SLOW_MACHINE, TIMEOUT, VALGRIND, DEVELOPER, DEPRECATED_APIS  # noqa: F401
 from pyln.testing.utils import env, only_one, wait_for, write_config, TailableProc, sync_blockheight, wait_channel_quiescent, get_tx_p2wsh_outnum  # noqa: F401
 import bitstring
+from pyln.client import Millisatoshi
 
 EXPERIMENTAL_FEATURES = env("EXPERIMENTAL_FEATURES", "0") == "1"
 COMPAT = env("COMPAT", "1") == "1"
@@ -53,6 +54,13 @@ def check_coin_moves(n, account_id, expected_moves, chainparams):
     moves = n.rpc.call('listcoinmoves_plugin')['coin_moves']
     node_id = n.info['id']
     acct_moves = [m for m in moves if m['account_id'] == account_id]
+    for mv in acct_moves:
+        print("{{'type': '{}', 'credit': {}, 'debit': {}, 'tag': '{}'}},"
+              .format(mv['type'],
+                      Millisatoshi(mv['credit']).millisatoshis,
+                      Millisatoshi(mv['debit']).millisatoshis,
+                      mv['tag']))
+
     assert len(acct_moves) == len(expected_moves)
     for mv, exp in list(zip(acct_moves, expected_moves)):
         assert mv['version'] == 1