Pycoin

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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

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* major overhaul of the VM and scripting system to make it more compatible with bitcoind
including added over 1000 tests from bitcoind
* added a framework to trace transaction script
* removed chain.com service provider, as they've disabled their API
* removed biteasy service provider, as many transactions were not being returned properly
and there are many other good alternatives
* deprecate PYCOIN_SERVICE_PROVIDERS in favor of PYCOIN_BTC_PROVIDERS
* add Peter Gray's message signing code to pycoin/contrib
* add experimental bitcoind_disk code to read blocks from bitcoind disk database
* deprecate Tx.tx_from_hex (instead use Tx.from_hex)

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* fix a problem creating and parsing scripts with blobs of size >= 256

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* more tests
* prototype support for using native OpenSSL methods to speed up some slow operations.
Set (and export) environment variable PYCOIN_NATIVE=openssl to activate.
* moved intbytes to pycoin.intbytes
* support signing pay-to-scripthash in tx utility
* abolish support for negative numbers in BIP32 key paths
* more networks
* changed how Spendable streams to text and to dicts to put transaction hashes in the
more conventional order. ** WARNING **: if you have built databases of Spendable objects
using these methods, you will need to convert them
* make spend.py script obsolete
* first crack at Insight service, chain.so service, chain.com service
* deprecate Tx.tx_from_hex in favor of Tx.from_hex
* a zillion other minor fixes

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* more networks
* moved some (untested) network code from pycoinnet
* fix a bug in Key which affected ku, and add a unit test (thanks to Michael Perklin for the report)

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* add pycoin.blockchain (which was in github but not setup.py)