ERC-3345: Call chaining

I’ve drafted a new standard to replace ERC667 and ERC1363, as well as an alternative to ERC777. It goes a bit further even in that it is not limited to token transfers, but can be applied to any smart contract:

It is inspired on the ENS multicall pattern, but adding a user-provided abi-encoded function call from the smart contract that the user interfaces to, to an user-specified receiver.

There are some safety and implementation challenges to this standard, but I think they can be overcome. I think that the gas savings and UX improvements are worth it.