Better tables, improved output quality, header levels

Tables!

• Integrate custom table model for better table rendering - this uses a new state of the art open table model

Markdown output

• Adjust block detection to improve markdown output globally
• Assign layout labels to blocks in a better way - will improve quality globally
• Better line spacing in markdown output
• Push footnotes to end of page

Header levels

• Add detection for header levels like #, ##, etc.
• Add computed table of contents

Bugfixes/misc

• Fix bug with pagination not working
• Much better debugging with debug image output
• Python 3.13 support