Many cleanups to Transaction, see detailed.

Default-ize the sequence rather than use a number, and default to bytes
for input. I doubt anybody ever uses this anyways.

Remove weird convenience code, and remove wallet logic. Checking a TX's
affects on a wallet should be managed by the wallet object.

Remove parsing for the weirder SIGHASH types. People use this library
for creating SIGHASH_ALL transactions, and I don't see the need to
support these other types at the moment since this library's more used
for wallets than for hardcore bitcoin tx analysis/creation. They weren't
tested anyways.

Add note about potentially improving performance by providing
pubkey/address. Deriving from the private key is slower, that
information should probably be cached by the end user.
add back SIGHASH code to transaction
Merge pull request #76 from coinpunk/transactioncleanups

Many cleanups to Transaction, see detailed.
Adds failing test for #78
Fixes #78
Merge pull request #79 from Dcousens/master

Fixes #78 for alternative constructor syntax
Changes to new version-less ECKey API
Restructures test/eckey.js
Fixes network tests for proper address types
Merge pull request #80 from Dcousens/versionextract

Extracts version from ECKey private/public key utility class
upgrade crypto-js (uglified source no more)

thank you @evanvosberg, @kyledrake. [evanvosberg/crypto-js#6]
Changes default EC*Key.toString behaviour to Hex
Renames variables to better reflect their values
Changes expected key output to hex
Merge pull request #81 from Dcousens/tostring

EC*Key.toString now returns hex instead of WIF
tabs -> spaces
Removes unused variables
Various stylistic changes
Fixes variable redeclarations
Uses Array.prototype.foreach for stricter scoping