* Hold a ref to the fee estimator when the Mempool is destroyed and re-created. Unify the sharing of information between Mempool and MempoolManager
* Adjust tests to new Mempool create interface
* Store dynamic Mempool info in the FeeEstimator and static info in the Mempool
* Adjust tests
* Restore logging of block cost % calculation to use documented full block size
* Omit check for nil self.last_mempool_info
* Annotate Mempool members
* Add integration test for add_mempool_item
* Annotate types in BitcoinFeeEstimator class