Release Candidate Changelog

Release 0.6 Changes

Simplified priceFeed, with governance over primary oracle. Hybrid solution uses the existing PriceFeed mechanics (which combines dual chainlink feeds with validity state machine + potential backup oracle) as the primary oracle in the new design.
Rounding issue scope verification and research project around potential rearchitectures
- Practically mitigated by enforcing a 1000 wei minimum debt, and 1000 wei minimum change of debt. There is also a 1000 wei minimum change of collShares on user operations.
New TWAP on totalDebt to prevent spot manipulation of totalDebt via flashloan to reduce redemption fee scaling.
Governance work on timelock and configuration of highsec / lowsec timelocks.

#720 Mid-contest fix for Certora prover
#737 Introduce simplified "brainead" oracle
#727 Fixes for Leverage macro, now used as a basis for Zaps
#721 Forge coverage doesn't work with multiple complier versions, resolved so we can use it
#730 Track the source CDP for each collSurplus as well as independenly account for collateralShares and liquidatorRewardShares
#725 Reinsert partially redeemed CDP after all fully redeemed CDPs are removed
#742 Implement more view functions on Governance
#741 Allow flashLoans to be called in TargetFunctions (oversight), and clamps partialRedemption parameters to create more valid runs.
#739 Made test Collateral function exactly like stETH
#723 Braindead Oracle primary PR with Echidna Tester
#747 Enforce minimum 100 wei debt, and 1000 wei changes for debt, along with required test modifications.
#722 Add timelocks and lowsec / highsec governance configuration
#736 Minimum viable TWAP - track totalDebt value over time to prevent spot manipulation of totalDebt via FL to reduce redemption fee at scale
#744 Rename braindeadFeed to eBTC feed

CdpId's array was removed as it's sole purpose was to allow random access on-chain into list which was deemed not worth of storage.
Combined with switching liquidatorRewardShares to a uint128, it frees up a storage slot write on Cdp opens which is meaningful optimisation at low risk.
A new chainlink adapter combines the ETH/USD and BTC/USD feeds to get the ETH/BTC price, rather than using that feed directly.
The stETH:ETH rate is now read as a fixed 1:1 by default, rather than the market rate. There is a governance ability to switch the feed to the market rate oracle.

#760 removes CdpId's array for random access into list to free up storage space
#759 lastGoodPrice is no longer stored on priceFeed contract, just on EbtcFeed
#761 prevents authority address from being changed on all system contracts except governor.
#762 cap liquidator reward shares at uin128 to free up one storage slot (when combined with removal of CdpIds array)
#763 Chainlink adapter to combine ETH/USD and BTC/USD feeds to ETH/BTC
#767 some governance changes, see PR
#777 More precise properties around debt and collateral rounding behavior
#779 TWAP emergency switch in case of revert
#780 Fix sequenceLiqToBatchLiq inequality to test recovery mode