[WIP] Async wrapper

[nelstrom]

Fixes issue #3.

[prabirshrestha]

@nelstrom a:message in neovim is an array where value is separated by \n. async.vim normalizes it to array even for vim8 so you need to join by \n. I do this in the async.vim sample (will update the docs to be clear about this)

function! s:job_err_cb(name, channel, message) abort
  echohl WarningMsg
  echom a:name . ': ' . join(a:message, "\n")
  echohl None
endfunction

[nelstrom]

@prabirshrestha thanks for the advice!

[nelstrom]

@prabirshrestha I'm a bit confused about what arguments are provided to the callbacks. In NeoVim, it looks like the callback receives arguments s:JobHandler(job_id, data, event) (from :help job-control-usage). I'm not sure what would be the equivalent in Vim8. Or does async.vim normalise Vim8 callback args to be the same as in NeoVim?

[prabirshrestha]

async.vim normalizes vim8 to neovim so you get the the same as neovim. s:JobHandler(job_id, data, event).
Feel free to send a PR in async.vim to add docs or improve README.md

[k-takata]

@nelstrom
Can you try async-wrapper branch?

[prabirshrestha]

i fixed the bug on upstream async.vim. You would want to sync this with latest master.

[k-takata]

I created a new PR based on this. See #5.