Parse genesis file to create a Chain object

[carver]

What is wrong?

Would be ideal to be able to create a Chain object from a genesis file. This implementation already exists in Trinity, but more reasonably belongs in py-evm. Tools like eth-tester would benefit from this functionality. See user request at: https://github.com/ethereum/web3.py/issues/1677 (inspired by desire to set the chain ID for an eth-tester chain)

How can it be fixed

Import the same logic from Trinity's trinity/_utils/eip1085.py. (and presumably there are tests in Trinity that can be ported in)

[carver]

@kclowes I guess you're probably blocked on Felipe for London work anyway, so maybe you could start on this?

[kclowes]

I'll take a look on Monday!