* Rename current ERC721 implementation to BaseERC721
* Implement ERC721 optional & approveAll functionality
* Support for new ERC721 interface
- Tests for new features are pending
- ERC721 is abstract, since it requires metadata implementation
- Move some methods into DeprecatedERC721 contract
- Reorganise base vs full implementation
- Pending tokenByIndex
* Add more tests for ERC721
* Implement suggestions by @dekz
* Update comments in ERC721 contracts
* Implement tokensByIndex extension
- Remove restrictions from mock mint and burn calls
* Add default implementation for metadata URI
This allows token implementation to be non-abstract
* Allow operators to call approve on a token
* Remove gas stipend restriction in call to 721 receiver
* Remove deprecated implementation
We only want to keep the interface, for interacting with already deployed contracts
* Add notice to isContract helper on constract constructors
* Change natspec delimiters for consistency
* Minor linting fixes
* Add constant modifier to ERC721_RECEIVED magic value
* Use 4-params safeTransferFrom for implementing the 3-params overload
* Minor text changes in natspec comments
* Use address(0) instead of 0 or 0x0
* Use if-statements instead of boolean one-liners for clarity
:-(
* Keep ownedTokensCount state var in sync in full ERC721 implementation
* Fix incorrect comparison when burning ERC721 tokens with metadata
* Use address(0) instead of 0 in one more place in ERC721
* Throw when querying balance for the zero address
Required by the spec
* Update links to approved version of EIP721
* Use explicit size for uint
* Remove unneeded internal function in ERC721
Also rename addToken and removeToken for added clarity
* Use underscore instead of 'do' prefix for internal methods in ERC721
* Fix failing test due to events reordering in ERC721 safe transfer
* Fix bug introduced in 74db03ba06
* Remove do prefix for internal setTokenUri method
* Allow transfers to self in ERC721
add missing public identifier in approveData in SmartToken contract
remove constact from showMessage function in message helper contract
move Message helper contract to mocks folder
move SmartTokenMock contract to mocks folder
Throwing when trying to burn 0 tokens is an unnecessary special case.
If another contract wants to burn() a variable amount, it should not be forced to deal with this special case of burning 0.
