ERC-6551: Non-fungible Token Bound Accounts

ERC-6551 proposes a system that assigns an Ethereum smart contract account to every non-fungible token, so NFTs can own assets and interact with applications without changes to existing NFT contracts. The proposal defines a singleton registry that computes and creates these token bound accounts, with each account permanently bound to one NFT and controlled by that NFT's holder. The registry is described as permissionless, immutable and ownerless, and it is to be deployed at a specified address using Nick's Factory. Each account is an ERC-1167 minimal proxy whose deterministic address derives from its implementation, salt, chain ID, token contract and token ID.