upgrade bigi & remove monkey patching
Remove Number.isFinite check on tx input index
Merge pull request #166 from bitcoinjs/remove-isfinite-check

Remove Number.isFinite check on tx input index
Merge pull request #165 from bitcoinjs/bigi-monkey-patching-no-more

Upgrade bigi & remove monkey patching
Variables names made consistent with constructor
Removes unnecessary new Buffer
Fixes #167 and adds temporary test
Merge pull request #168 from dcousens/167fix

Fixes #167
Stretches test for derive m/0 from xpub
Changes sequence number to an actual Number
Changes fakeTxHash to actual hex
Serialize now returns a buffer
Adds Buffer extensions
Changes internal serialization to use Buffers instead
Adds performance notes
Corrects endianness comments