Improvements to OverloadedMethod

[iamdefinitelyahuman]

Overview

1. OverloadedMethod should infer which method is being called, based on the given inputs.
2. It should be possible to iterate over the functions within OverloadedMethod.

Related: https://ethereum.stackexchange.com/questions/79505/what-is-a-good-alternative-to-contracttranslator-encode-abi

Specification

As an example, consider the ERC223 transfer function, which is possible as (address,uint256) and (address,uint256,bytes).

>>> erc223.transfer
<OverloadedMethod object 'ERC223Token.transfer'>

The following examples should all work:

>>> erc223.transfer(accounts[0], 1000)
>>> erc223.transfer(accounts[0], 1000, "0x1234")
>>> erc223.transfer.encode_abi(accounts[0], 1000, "0x1234")

An important consideration is that Brownie is fairly loose with types. There could be situations where it is not possible to determine the correct function from the given inputs. It could be possible to use stricter type checks, but if that's inconsistent with how everything else works - maybe better to just raise and demand explicitness.