Merge pull request #1675 from evoskuil/master

Fix witness non-assignable due to annex reference.

Refactor all signature_hash methods to return bool (tapscript).

Add witness.is_annex_pattern() and refactor witness.

Refactor chain into small src/ipp files, stub in v1 sighash cache.

Merge pull request #1673 from evoskuil/master

Refactor all signature_hash methods to return bool (tapscript).

Merge pull request #1672 from evoskuil/master

Fix sha midstate, complete sha256t_writer, add tests.

Merge pull request #1369 from pmienk/version3

Regenerate with updated version to 3.8.0.

Change from boost::filesystem to std::filesystem.

Merge pull request #1131 from thecodefactory/build-update

Regenerate build artifacts.

Various updates.