Phmdoctest

- Add feature to generate test files using a configuration file.
- Add `<--phmdoctest-mark.ATTRIBUTE-->` directive.
- Add tool to check for Python examples.
- Add tool to prepare a generated test file output directory.
- Bugfix- issue- pytest not required for installation.
- Combined CI script install.yml into ci.yml.
- Close open files in test_readthedocs_python_version().

- Add main.testfile().
- Add testfile_creator and testfile_tester fixtures.
- Bugfix- Issue- Generated test name has output_NN when skip
directive on output block.
- Bugfix- Issue- mark.skipif example code causes pytest AST fail at
assertion rewrite time. Happens on skipped Python version.
Replaced with code that compiles on the skipped version.
- Drop Python 3.6 add Python 3.10.

tests:

- Add mode=0o700 to mkdir() calls in test .yml files.
- Run tests in virtual envirionments. ci.yml.
- Add test_details.py.
- Add Appveyor to CI to show pytest items.
- Rework requirements files. Add tests.
- Refactor new fixtures to conftest.py.
- Rework/refactor quick_links test logic.
- Add test to find trailing spaces in sources.
- Tox no longer used in test suite.

docs:
- Bugfix- Issue- Markdown header level out of sequence.
- Loosen doc dependencies.
- Fenced code block info_string pycon -> py.
- Sphinx with myst_parser for docs.

style:
- Style/pep8/inspection fixes.
- Path and open changes.
- Remove trailing spaces from ~25 files.

- Bugfix- 16, 15, Issue- Simulator subprocess failed on win venv.
- Code Quality fixes: assert --> raise.
- Make fenced code block info_strings compatible with GitHub pages.
- Restored tox.ini.

- Add inline annotations.
- Reformat code style with black.
- Rework setup.py/setup.cfg.
- Remove tox.
- Fix bad example in README.md.

- Bugfix- Pull Request 6, Issue 8 --outfile missing `import pytest`.
- Documentation typo fixes.

- Add test directives taken from HTML comments in .md.
- Implement setup/teardown with Pytest fixtures.
- Use difflib.ndiff to show unexpected output.
- Add simulator feature to return JUnitXML from pytest.