Add BIP32 bitcoinjs implementation

[dcousens]

Also formats the list for readability

[dcousens]

ping @sipa, thoughts?

[sipa]

Per https://bitcoincore.org/en/meetings/2016/05/12/ please link to actual implementation code for BIP32, and not just applications that support it.

[dcousens]

@sipa not sure what you mean? The link added was implementation code for BIP32?

This was the link added: https://github.com/bitcoinjs/bitcoinjs-lib/blob/v2.1.4/src/hdnode.js
Perhaps I'll rebase and isolate the formatting commit from the addition.

Jcorgan proposes to link to an URL and commit hash, to make sure the linked code reflects the implementation.

Is the commit hash preferred over the tagged version used above? If so, I'll change it.

[afk11]

I haven't seen commit hashes included much before, just a link to the implementation's file or repo.

Re sipa's comment, probably refers to mentioning blockchain.info's use of the bitcoin-js implementation; that information is not typically included in BIP documents. 681c160

There is also another PR (#293) which reformats the BIP32 implementation list, perhaps coordinate so there's only one large update?

[dcousens]

Re sipa's comment, probably refers to mentioning blockchain.info's use of the bitcoin-js implementation; that information is not typically included in BIP documents. 681c160

Right! I totally forgot that those commits were included into this.
I'll re-submit a new PR that performs the implementation reference.

If #293 is just a formatting PR, perfect. Otherwise, I'll submit that independently.