* replace bitvec with more efficient bitpack algorithm
* optimise proof_unpack_len
* move proof pack length calculation
* small refactor
* first pass attempt at not deserializing proof nonces in difficulty iter
* another 10 seconds gained by not deserialising the proof from the difficulty iterator
* add new deser parameters to tests where needed
* add skip_proof variants to store
* remove hash from difficulty iterator struct, rename HeaderInfo to HeaderDifficultyInfo
* replace bitvec with more efficient bitpack algorithm
* optimise proof_unpack_len
* move proof pack length calculation
* small refactor
* first pass attempt at not deserializing proof nonces in difficulty iter
* another 10 seconds gained by not deserialising the proof from the difficulty iterator
* add new deser parameters to tests where needed
* add skip_proof variants to store
* remove hash from difficulty iterator struct, rename HeaderInfo to HeaderDifficultyInfo
* More efficient serialization for bitmap segments
* Rename a const
* Correctly count number of chunks in a segment
* Enum for BitmapBlock (de)ser mode
* Add more segments in test
* Fix duplicate function
