This is the first in a sequence of changes that change the block:: items
to not include Block as a prefix in their name, in accordance with the
Rust API guidelines.
This extracts the SHA256d code from being split across two modules and puts it
in one module, under serialization.
The code is unchanged except for three deleted tests:
* `sha256d_flush` in `sha256d_writer` (not a meaningful test);
* `transactionhash_debug` (constructs an invalid transaction hash, and the
behavior is tested in the next test);
* `decode_state_debug` (we do not need to test the Debug output of
DecodeState);
* create hash submodule for block
* create header submodule for block
* create serialize submodule for block
* add newline to hash.rs (fmt)
* Update zebra-chain/src/block/tests.rs
Co-authored-by: Jane Lusby <jlusby42@gmail.com>
Co-authored-by: Henry de Valence <hdevalence@hdevalence.ca>
Co-authored-by: Jane Lusby <jlusby42@gmail.com>