* graphql, internal/ethapi: extend eth_call
This PR offers the third option parameter for eth_call API.
Caller can specify a batch of contracts for overriding the
original account metadata(nonce, balance, code, state).
It has a few advantages:
* It's friendly for debugging
* It's can make on-chain contract lighter for getting rid of
state access functions
* core, internal: address comments
gary rong
c9cdf144d5