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* add tx --db option to include source transactions
* add pycoin.contrib.who_signed module
* use latest version of tests from bitcoind (script_tests.json, tx_invalid.json,
and tx_valid.json)
* add CHECKSEQUENCEVERIFY working
* add initial support for segregated witness ("segwit")
* rename scripts module to cmds to eliminate confusion with bitcoin script module
* remove obsolete commands genwallet, bitcoin_utils and spend
* changed to more standard "M of N" for multisig
* move networks.py to networks module
* add network/registry.py to allow dynamic registration of non-bitcoin networks
* move messages.py to messages module
* add electrum key support to ku tool
* add bloomfilter.py
* add recipies for multisig