allow manually providing pubkeys for multi‐sig (fixes #413)
Cleanup of `transaction.construct()`

- Clearer logic
- PEP 8
Merge pull request #490 from CounterpartyXCP/413

Allow manually providing pubkeys for multi‐sig
reverse hash
Merge pull request #545 from ouziel-slama/develop3

reverse hash
Merge pull request #544 from ouziel-slama/develop

use RPC batch for unconfirmed_transactions()
typo