Feature: Add g:vimtex_syntax_custom_envs

[lervag]

This should resolve #2745.

[GergelyKalmar]

I'm seeing the following error when switching to this branch:

Error detected while processing function vimtex#syntax#core#init_post[12]..vimtex#syntax#packages#init[20]..vimtex#syntax#core#init_custom[12]..vimtex#syntax#core#new_env[19]..vimtex#s
yntax#core#new_env:
line   70:
E399: Not enough arguments: syntax region start="\\begin{\z(code\)}\s*\[\_[^\]]\{-}language=python\_[^\]]\{-}\]" end="\\end{\z1}" contains=texCmdEnv,@vimtex_nested_python keepend

Config:

let g:vimtex_syntax_custom_envs = [{
      \ 'name': 'code', 'nested': {
      \   'python': 'language=python',
      \ }}]

[lervag]

Thanks, I fixed both of those now. Note, though, that the latter issue is really due to you forgetting to pass the region key. But I realize that VimTeX can just forgive that and create a region name based on the "name" key.

[GergelyKalmar]

Ah, I see! I think creating the region name is perhaps even better. It works perfectly fine now! Perhaps the region argument can be marked now optional in the documentation?

[lervag]

Thanks; I've made a minor adjustment to the docs regarding the region name. And I merged this, since it seems good enough for now :)

[GergelyKalmar]

Awesome, thank you very much for the feature! Works perfectly fine.

[lervag]

Glad to hear it :)