UI improvements and steps towards a more complete Windows support

What's Changed

• Code climate: improve css fix html rendering for ordered list by @gioboske in #654
• CI: set up correct dependencies for periodic checking of dead links by @stanislaw in #656
• docs: split the documents: User Manual, Requirements and Backlog by @stanislaw in #657
• export/html: support sections without a level by @stanislaw in #651
• tasks: fix dead links task by @stanislaw in #658
• requirements.development.txt: relax all dependencies to >= by @stanislaw in #659
• requirements.txt: relax all dependencies to >= by @stanislaw in #660
• docs: extract goals to the development plan draft by @stanislaw in #661
• tasks: reset PATH when running from virtual environments by @stanislaw in #663
• tasks: do not reset the PATH when running sphinx task by @stanislaw in #664
• feature: import excel by @BenGardiner in #662
• tasks: stop using @task for cleaning the itest artifacts by @stanislaw in #666
• backend/excel: keep import and export together by @stanislaw in #667
• requirements.txt: constraint most of the deps to the same major version by @stanislaw in #668
• Code climate: mypy: enable --strict and disable remaining checks by @stanislaw in #669
• Code climate: mypy: fix the "assignment" errors by @stanislaw in #670
• Code climate: try * to enforce named parameters by @stanislaw in #671
• Code climate: tests/integration: prepare test folders by @stanislaw in #672
• excel/import: optional title for imported documents by @BenGardiner in #673
• docs: small update in the dev plan by @stanislaw in #674
• developer/design: add a sketch (Affinity Design) by @stanislaw in #676
• HTML export improvements by @BenGardiner in #677
• traceability: source_files_finder: ignored_dirs argument and unit test by @stanislaw in #678
• traceability: simplify handling of source file paths by @stanislaw in #679
• export/html: table-based requirement template by @stanislaw in #680
• tasks: fix the "The command line is too long." issue on Windows by @stanislaw in #682
• tasks: check_environment: un-hardcode python3 because it fails on Windows by @stanislaw in #683
• export/html: link_renderer: always print forward slashes (Windows) by @stanislaw in #684
• tasks and tests/integration: portable clean, %cat, and %diff by @stanislaw in #685
• tests/integration: Python version of cat to make it portable by @stanislaw in #686
• tests/integration: Python version of 'touch' and 'mkdir' to make them portable by @stanislaw in #687
• tests/integration: Python version of 'cp' and 'rm' to make them portable by @stanislaw in #688
• export/html: integration test for UTF8 symbols in SDoc by @stanislaw in #689
• tests/integration: improve rm.py by @stanislaw in #690
• tasks: on Windows: detect if Bash is available by @stanislaw in #691
• file traceability: improve handling of Windows-style paths by @stanislaw in #692
• tests/integration: move away from a grep-based test by @stanislaw in #693
• docs: update documentation, introduce design document by @stanislaw in #694

New Contributors

• @gioboske made their first contribution in #654

Full Changelog: 0.0.23...0.0.25