* Convert BlockGHOSTDAGData from an interface to a public struct with getters
* Move hashes.Less to externalapi so it can access the hashes directly without copying
* Reduce calls to ghostdagstore.Get in blueWindow
* Simplify the logic in RequiredDifficulty and reuse big.Int
* Remove bigintpool as its no longer used
* Use ChooseSelectedParent in RequiredDifficulty instead of looping over the parents
* Remove comment
* [NOD-1528] Make data stores copy data on stage
* [NOD-1528] Add proto objects to serialize consensus state objects
* [NOD-1528] Fix receiver names
* [NOD-1528] Add copy to block store and utxo diff staging
* [NOD-1528] Return errors where needed
* [NOD-1461] Change the external api interface to not having anything besides DomainTransactions and DomainBlocks.
* [NOD-1462] Move external api types to a separate package.
* [NOD-1462] Clarify which model we're using in miningmanager.
* [NOD-1462] Extract coinbase data to its own struct.
* [NOD-1462] Add a comment above CoinbaseData.
* [NOD-1462] Fix the comment above CoinbaseData.
* [NOD-1458] Rename RestoreUTXOSet to RestorePastUTXOSet.
* [NOD-1458] Make CalculateAcceptanceDataAndMultiset take BlockGHOSTDAGData and nothing else.
* [NOD-1458] Make ConsensusStateStore's Update take ConsensusStateChanges instead of just UTXODiff.
* [NOD-1458] Add Tips() to ConsensusStateStore.
* [NOD-1458] Make all implementation structs private.
* [NOD-1458] Remove BlockAtDepth and add highHash to ChainBlockAtBlueScore.
* [NOD-1458] Rename CalculateAcceptanceDataAndMultiset to CalculateAcceptanceDataAndUTXOMultiset.
* [NOD-1458] Add a dependency to GHOSTDAGManager from ConsensusStateManager.
* [NOD-1458] Add ChooseSelectedParent to GHOSTDAGManager.
* [NOD-1458] Add DifficultyManager.
* [NOD-1458] Add PastMedianTimeManager.
* [NOD-1458] Add Hash() to Multiset.
* [NOD-1458] Add a dependency to ghostdagManager from blockProcessor.
* [NOD-1458] Add errors to all interfaces that need them.
* [NOD-1458] Uppercasify types in comments.
* [NOD-1458] Fix a bad comment.
* [NOD-1458] Fix a comment.
* [NOD-1458] Rename ChainBlockAtBlueScore to HighestChainBlockBelowBlueScore.
* [NOD-1458] Replace BlockAndTransactionValidator with an anonymous interface.
* [NOD-1416] Move processes/datastructures interfaces into the model package.
* [NOD-1416] Decouple the model from dbaccess.
* [NOD-1413] Implement DomainBlock and DomainTransaction.
* [NOD-1413] Decouple model from appmessage.
* [NOD-1413] Decouple model from util.
* [NOD-1413] Decouple model from subnetworkid.
* [NOD-1413] Remove an unused const.
* [NOD-1413] Add DomainHash and DomainTransactionID.
* [NOD-1413] Decouple model from daghash.
* [NOD-1413] Decouple model from mstime.
* [NOD-1413] Decouple model from go-secp256k1.
* [NOD-1413] Add a proxy over dbaccess.
* [NOD-1413] Add comments over all added types.
* [NOD-1413] Fix a comment.
* [NOD-1413] Get rid of DomainTime.
* [NOD-1413] Simplify BlockGHOSTDAGData.
