* make _tokenId indexed in Transfer and Approval events via: https://github.com/ethereum/EIPs/pull/1124/files * fix: make name() and symbol() external instead of public * feat: implement ERC721's ERC165 * feat: erc165 tests * fix: don't use chai-as-promised in direct await * fix: reorganize to /introspection * feat: abstract all erc165 tests to a behavior * feat: disallow registering 0xffffffff