Add quartable filter

[zinc75]

Adds quartable, a Quarto filter that extends Markdown pipe tables with column spans, row spans, midrules, partial clines (cmidrules), vertical lines and per-cell alignment overrides — targeting HTML, Reveal.js and PDF/LaTeX from a single source. The design is heavily inspired by the LaTeX booktabs package (rule weights, no per-row borders, partial rules via \cmidrule, etc.).

• Repository: https://github.com/zinc75/quarto-quartable
• Live demos (HTML / PDF / Reveal): https://zinc75.github.io/quarto-quartable/
• License: MIT
• Already listed in mcanouil/quarto-extensions.

[cscheid]

I don't think your project's name runs afoul of our trademark policy, but it feels close enough to doing so that I'm going to ask you to read the policy and acknowledge it: https://quarto.org/trademark.html

[zinc75]

I don't think your project's name runs afoul of our trademark policy, but it feels close enough to doing so that I'm going to ask you to read the policy and acknowledge it: https://quarto.org/trademark.html

@cscheid : I've read the trademark policy as requested. quarto-quartable is a quarto extension (therefore promoting the use of Quarto and improvement of Quarto functionalities), is non-commercial, is open-source (MIT licensed), therefore I of course acknowledge the trademark policy :-)

Almost every extension or filter has "Quarto" in its name, including this one. "Quartable" is a wordplay in French: "Quarto-table" -> "Quartable" (which sounds like "cartable," the French name for "schoolbag").

Best regards,