Make CBase58Data.from_bytes() not require a checksum

Also improve test coverage
Add dummy bitcoin.core.key.CPubKey class
Add CBitcoinAddressError exception
Add CScript.to_p2sh_scriptPubKey()
Merge commit '5a0380a9cb83cb2960d9f440174828b831ad4e4e'
Add checksize option to CScript.to_p2sh_scriptPubKey()
Merge commit '6d5758a36fecf71c89d7486aafdb2ac521100185'
Fix up CBase58Data initialization so subclasses can use __init__()
Document Bitcoin Core version requirement
Update script_(in)valid.json

From Bitcoin Core ffd082a6a36bf0b85078be8400b8eda3630b34b3
Make FindAndDelete() publicly available

Needed for experimentation with OP_CODESEPARATOR etc.
Update script_(in)valid.json

From Bitcoin Core d3a33fc869d23fb13c010a6e9995bdf6574a621e
Fix CHECKMULTISIG consensus bugs
Merge commit '675ea5715f99e83a7d62e4ff6326d4766bc6700d'
Merge branch 'master' of github.com:petertodd/python-bitcoinlib
add fixme notes re: codeseparator/findanddelete bugs
Initial split of pubkey and seckey functionality

Secret key stuff now in CBitcoinSecret in non-consensus-critical
bitcoin.wallet module.
Add some examples of spending transaction outputs
Update readme
Add pay-to-pubkey-hash to CBitcoinAddress.from_scriptPubKey()