tests: Big push to get the tests to pass again. - Lots of fixes everywhere in the code. - Try to handle debug logging in the multiprocessing worker pool when running in pytest. Not perfect, but usable for now. - Replace all `.md` test files with `.html` since now a auto-format extension always sets the format. - Replace `out` with `outfiles` in most places since now blog archives are added to the bake output and I don't want to add expected outputs for blog archives everywhere.

include CHANGELOG.rst
include INSTALL.rst
include LICENSE.rst
include README.rst

include pytest.ini
include setup.cfg
include requirements.txt
include dev-requirements.txt

recursive-include piecrust *
recursive-include tests *

global-exclude *.py[cdo] __pycache__ *.so
global-exclude .DS_Store Thumbs.db Desktop.ini
global-exclude *.swp *~ *.bak