line-numbers-init for code chunks in reveal.js

[maxpel]

Description

It would be great to have the option to start code line numbering at a different value than 1, especially when working with reveal.js slides as sometimes we have to split up longer code chunks over multiple slides when presenting.

A chunk option like code-line-numbers-init would solve that, for example:

#| code-line-numbers-init: 30

That suggestion follows the reveal.js plugin: https://github.com/mikemiles86/reveal-line-numbers

[mcanouil]

Closing in favour of:

• [FR] Support line number offset for code blocks in revealjs #1454