[PATCHES 1, 2/2] allow to use document title in agenda and refile outline paths

[Mikhail Skorzhinskii]

Hello everyone,

I've already submitted these features to the mailing list:

  https://lists.gnu.org/archive/html/emacs-orgmode/2020-09/msg00628.html

But even if these changes are really tiny and minor, they are touching very 
different functionality of org-mode. It wasn't good mixing my suggestions for 
agenda and for ox-icalendar. So I'm starting a separate mail thread.

Changes since v1:
  - Allow to customise title path for the refile targets also (thanks to Ihor 
Radchenko for suggestion);
  - Turn separate option into just an additional value for 
org-agenda-show-outline-path.

Kind regards,
Mikhail Skorzhinskii