Fix/oz30

[alcueca]

It took me a while to update everything to work with OpenZeppelin contracts 3.0, some tricks they threw in, including changing the ERC20 constructor signature.

I actually had to discard some 20 commits and branch from a branch to try a different approach.

And they broke one of my toys, I had to do some hard stuff to fix Democracy.sol :(

[alcueca]

@obernardovieira, any idea why this fails? It works locally and I updated my packages using yarn.

[vibern0]

The problem is around the erc165 checker, which I do not have much experience, but I've seen a couple of things.

1. in ERC20Whitelisted you are extending ERC20 without calling its constructor. Any reason for that?
2. WhitelistInterfaceId might be abstract.
3. in WhitelistERC165 you are extending ERC165. How ERC20Whitelisted is different from WhitelistERC165 and why isn't one extending the other?
4. In ERC20Whitelisted's constructor, how can you call _ERC165Checker.supportsInterface, since _supportsInterface is internal and ERC165Checker is a library? I'm a bit confused.

I had exactly the same problems as the CI and after adding ERC20 constructor (from 1.) and removing the "require" in ERC20Whitelisted constructor, it worked (with one exception). I just don't know how you want to fix it.

 274 passing
  1 failing

  1) Contract: ERC20Whitelisted
       constructor throws if called with an address not implementing IWhitelist.:
     AssertionError: expected to throw, did not: expected false to be truthy
      at Context.<anonymous> (test/utils.js:14:20)
      at runMicrotasks (<anonymous>)
      at processTicksAndRejections (internal/process/task_queues.js:97:5)

[alcueca]

Next time CI gets different results than my local machine, I should remember to remove the build folder and recompile.

Once I got the errors in my machine it was easy to fix. OpenZeppelin just changed the constructor for ERC20 and renamed that function in ERC165Cheker.

[vibern0]

I should remember to remove the build folder and recompile

ahah that usually helps 😂
awesome, congrats for this work 👏