Simplify Libra.move (or replace)

[0o-de-lally]

We can radically simplify Libra.move

Since there are changes to stdlib/Libra.move, perhaps we should fork that file, and call it something like Coins.move, and place in /OL/. That way we could keep the original Libra.move, and pull in FB's changes to follow what is changing. (Although eventually think we need to not include it in genesis).

Some changes to Libra.move

• [ ] mint/burn/preburn/register/etc. capabilites in Libra.move. I think all of these are not useful, especially if we have only one address (Subsidy) that can mint and burn GAS.
• [ ] Preburning is not a workflow for us. There is just burning. Can remove all references including preburn marketcap.
• [ ] lbr_exchange_rate in Libra.move, Ratios/exchange rate to LBR is not a meaningful field for us, can remove from all types.
• [ ] isSynthetic is not meaningful to us. Can also remove.
• [ ] update_minting_ability in Libra.move. Can be commented out, perhaps keep as a reference.
• [ ] approx_lbr_for_value. not useful
• [ ] approx_lbr_for_coin. not useful
• [ ] Reserve in GasCoin.move is odd, I think it's not necessary if we will always have one address that can mint or burn the coins. Seems like a dangerous capability to maintain if we don't need it.

[liangping]

We can not have two Libra.move, even though they are in different directory. it will come up with duplicated module error.

[0o-de-lally]

Ok good point. My thought was to radically simplify Libra.move, or eliminate it as a dependency in favor of a "Coins.move". But I think we should let it stabilize a bit before these optimizations.

[0o-de-lally]

@nelaturuk Maybe you can revisit this now that we've got a good cleanup done, and removed association.