ERC721 implementation shouldn't extend from Ownable

[mg6maciej]

I have to say it IS convenient in my unit tests, that it does, but not all deployments will require it.

[MoMannn]

You are correct. We will move the Ownable to the mocks.

[MoMannn]

#98 @mg6maciej How does this look to you now? The implementation itself is without ownable but mocks have it.

[mg6maciej]

@MoMannn LGTM. If possible I would go with a bit different inheritance to avoid duplicating mint and burn in 4 mock contracts. Something like NFTokenEnumerableMock is NFTokenEnumerable, NFTokenMock.

[MoMannn]

@mg6maciej Ok, then I will close this issue. We will consider your suggestion about inheritance but that is a separate thing so I will open another issue for discussion about it.