Improve AbiFunction#parseSignature to cover more cases

[ArtificialPB]

Module

ABI

📝 Description

Parse function should also support parsing signatures which contain:

• input argument names
• output argument names

Both of these cases should parse to the same abi function definition:

function balanceOf(address) returns (uint256)
function balanceOf(address who) public view returns (uint256 balance)