Interestingly I’m getting this error:

ERC721.sol:54:5: TypeError: Function overload clash during conversion to external types for arguments.
function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external;
^ — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — -^

When using your Github contracts. Also, the JSON files aren’t in the github, and a number of the contracts in the Standard file are missing the .sol extension. Otherwise this has been a pleasure to read!