New features:
* Strikeout annotations are rendered using surrounding context for the deletion.
* Document layout is now inferred by default from pdfminer, `--cols` remains only as a fallback/override.
* Support for alternative page numbers, when present in the PDF.
* JSON output format, as an alternative to Markdown.
* `--keep-hyphens` option.
* Command-line options for custom layout analysis parameters.
Internal improvements:
* Significant refactoring.
* Type annotations.
* Added support for pluggable output formats.
Fixed:
* 42 crash on annotations with broken references
* 44 UTF8 output on Windows