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* if there is no `outpoint` default to coinbase `transactionIn`, 32 zero bytes, i.e. `0` as tx hash, `-1` as txIndex
* added `Transaction.defaultNetwork`, defaults to `mainnet`
* commented out `analyze()`
* commented out `getDescription()`
* refactored `TransactionIn` and `TransactionOut` into separate files
* changed dep from `sha256` to `crypto-hashing`
* changed dep from `convert-hex` to `binstring`