Add highlighting for vimwiki

[odd-is-yes]

considering nord plays so well with stuff light lightline I'm suprised you haven't added highlighting so that the headers and todo lists look good on vimwiki considering it's such a popular plugin.

[arcticicestudio]

Thanks for the great detailed feature request 👍

I'm always happy for any help to get a new port project started.

Please note that my current life situation doesn't allow me to spend as much time on my projects as before like announced on Twitter so I've added this port project to the Backlog Icebox for the time being. It might take some time to test things out, but I'll try to reserve some free time on the weekends.

[vdumitraskovic]

I don't use vimwiki as much, but this is looking kinda ok for me:

" Vimwiki
" > vimwiki/vimwiki
call s:hi("VimwikiLink", s:nord9_gui, "", s:nord9_term, "", "underline", "")
if !exists("g:vimwiki_hl_headers") || g:vimwiki_hl_headers == 0
  for s:i in range(1,6)
    call s:hi("VimwikiHeader".s:i, s:nord7_gui, "", s:nord7_term, "", "bold", "")
  endfor
else
  let s:vimwiki_hcolor_guifg = [s:nord7_gui, s:nord8_gui, s:nord9_gui, s:nord10_gui, s:nord15_gui, s:nord14_gui]
  let s:vimwiki_hcolor_ctermfg = [s:nord7_term, s:nord8_term, s:nord9_term, s:nord10_term, s:nord15_term, s:nord14_term]
  for s:i in range(1,6)
    call s:hi("VimwikiHeader".s:i, s:vimwiki_hcolor_guifg[s:i-1] , "", s:vimwiki_hcolor_ctermfg[s:i-1], "", "bold", "")
  endfor
endif

call s:hi("VimwikiList", s:nord15_gui, "", s:nord15_term, "", "", "")

@odd-is-yes can you try it, and see if anything is missing and/or looking bad?
We could tweak it and submit PR afterwards.