add 165 to 721 (#972)

* 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

contracts/introspection/SupportsInterfaceWithLookup.sol

@@ -0,0 +1,53 @@
+pragma solidity ^0.4.23;
+
+import "./ERC165.sol";
+
+
+/**
+ * @title SupportsInterfaceWithLookup
+ * @author Matt Condon (@shrugs)
+ * @dev Implements ERC165 using a lookup table.
+ */
+contract SupportsInterfaceWithLookup is ERC165 {
+  bytes4 public constant InterfaceId_ERC165 = 0x01ffc9a7;
+  /**
+   * 0x01ffc9a7 ===
+   *   bytes4(keccak256('supportsInterface(bytes4)'))
+   */
+
+  /**
+   * @dev a mapping of interface id to whether or not it's supported
+   */
+  mapping(bytes4 => bool) internal supportedInterfaces;
+
+  /**
+   * @dev A contract implementing SupportsInterfaceWithLookup
+   * @dev  implement ERC165 itself
+   */
+  constructor()
+    public
+  {
+    _registerInterface(InterfaceId_ERC165);
+  }
+
+  /**
+   * @dev implement supportsInterface(bytes4) using a lookup table
+   */
+  function supportsInterface(bytes4 _interfaceId)
+    external
+    view
+    returns (bool)
+  {
+    return supportedInterfaces[_interfaceId];
+  }
+
+  /**
+   * @dev private method for registering an interface
+   */
+  function _registerInterface(bytes4 _interfaceId)
+    internal
+  {
+    require(_interfaceId != 0xffffffff);
+    supportedInterfaces[_interfaceId] = true;
+  }
+}