Idea: stealth compatibility with other price feed interfaces

[aesedepece]

At this point, I tend to think that beyond our beloved ERC-2362, it wouldn't do any harm for these price feed examples to support some additional interfaces, even if it's a sort "secret" feature — we will keep encouraging users to use the ERC-2362 interface.

Namely, these are two oracle interfaces of interest:

// This one is interesting as a drop-in replacement of other oracle contracts 
interface MarinesOracle {
  function latestAnswer() external view returns(int256);
  function latestTimestamp() external view returns(uint256);
}

// This one is interesting as a simple and gas-cheap solution to fetching a value without caring about errors
interface PoorMansOracle {
  function value() external view returns(int256)
}

[aesedepece]

Trying to draw the attention of @witnet/devs into this discussion 👁️