Redeemable

[elv-serban]

Implements:

• a new Redeemable contract that allows add/remove and redeem of 'offers' (max 256 offers - using a uint256 as a bitmap)
• elv_tradable_full redeemOffer and redeemOfferSigned (override the Redeemable virtual method to require caller is owner of token, and implement the delegated call to redeemOfferSigned)
• added foundry forge test framework for subdirectory 'src'
  • foundry requires solc 0.6+ and we use 0.5 in the legacy code, which is why I set up a new directory for new code

Implementation notes:

• I created src/redeemable.sol and copied it under tradable/redeemable.sol with a few modifications:
  • MinterRole import path
• I created a dummy MinterRole contract in 'src/' so we can test redeemable.sol
• NB the entire contracts repo will be scrubbed cleaned and upgraded and at that time this problem will no longer exist

Remaining problems to solve:

• unify the two redeemable.sol files
• run full elvmaster test on the new elv_tradable functions

[elv-nate]

Aside from some small comments I made about testing which are MinterOnly, this looks good to me. The design unfortunately makes it hard to test redeemable tokens without a much more involved test, as you need a token to implement it and such.

[elv-Tom]

Very efficient, use a minimum of gas, and works perfectly. I added a script here : https://github.com/eluv-io/contracts/blob/redeemable/script/tradable/redeemable.s.sol Because the contract will not be deployed, we can add the 'abstract' key word for this contract.