* [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-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.