Synchronous process of pandoc in batch mode

[minyez]

This PR implements synchronous run of pandoc process when Emacs runs in batch mode.

It addresses #6, where the asynchronous pandoc process will be killed before successful conversion when the master process of Emacs exits. The feature is achieved by checking the noninteractive variable, following the suggestion in the issue.

[yantar92]

It looks like some of the changes have nothing to do with running pandoc synchronously. May you please cleanup the pull request, leaving only relevant parts? You can create a separate request with unrelated improvements.

[minyez]

Hi @yantar92 thank you very much for checking and sorry for late reply. I'm not experienced in lisp programming and hence not sure which parts are irrelevant. To make pandoc run synchronously in batch mode, I use call-process after branching out from the noninteractive condition. It would be appreciated to hear your opinion.

[yantar92]

Sorry, I confused things. May you please squash the commits into a single commit for easier review?

[yantar92]

[ It took me a while to reach this item in my todo list. ]

I am looking at the commit and feel that the same might be done easier.
What if you simply change org-pandoc-run-to-buffer-or-file to loop until process-status is not running when non-interactive? Then, other changes appear to be unnecessary.