Fix solc version check and update dependencies

• Updated to work with solc v0.8.x
• Dependency updates

Estimate gas and multi-contract Solidity

• -E / --estimategas to call the contract and return the estimated gas, rather than the result
• -n / --contractname to choose an individual contract name in a Solidity file with multiple contracts

Private txn support

• Support for Private transactions per Quorum JSON/RPC extension and EEA Enterprise Ethereum Client Specification 1.0
• Automatic detection of the ChainID for EIP155 externally signed transactions, using the common practice of assuming it matches the networkID (consistent with tools like MetaMask)
• Windows binary build

Initial release

0.1.0

Call transactions and return values