s/bitcoin/Bitcoin/
Change license to LGPL v3 or later

LGPL is compatible with any reasonable usage of the software. In
particular with security-related software users should demand access to
sourcecode for auditing.

Prior license for most code was MIT, which is compatible with LGPL. One
exception was bitcoin.rpc, which was LGPL v2 or later, so this relicense
brings us into 100% compliance with that code's license.
Ensure COutPoint subclasses can't lead to bad serialization

Previously the prevout instance's stream_serialize() method was called
by CTxOut.stream_serialize(), which could result in an invalid
serialization had the prevout instance been a modified subclass.

Consistent with out the VectorSerializer usage everywhere else ignores
the instance's serialization methods in favor of callee-defined methods.
Add __slots__ to Serializable base class

Previously all those __slots__ definitions were useless because the base
class added a dict to the instances.
Add __slots__ to mutable transaction classes
Create P2PKHBitcoinAddress and P2SHBitcoinAddress subclasses
Fix CScript.is_push_only() on pushdata w/ missing length fields

Previously was catching the wrong exception
Add CScript.has_canonical_pushes()
Accept non-canonical and bare-pubkey P2PKH scriptPubKeys
Release v0.2.1
Reset version for future development
Minor: typo
Add P2SHBitcoinAddress.from_redeemScript()
Add warning about the merkle-tree algorithm duplicate txid flaw

Lots of people read the Bitcoin Core codebase to learn more about
crypto; better to warn about flaws explicitly so they don't blindly copy
the code for other uses and create broken systems.
Fix script name
Move sys.version test out of x/b2x/etc. functions
use same name for function to load test data

The test data loading function was previously sometimes plural and
sometimes singular. This makes it always plural, because each file might
have multiple different vectors of test data.
Merge pull request #23

c9be341 use same name for function to load test data (Bryan Bishop)