org-export: Require info argument in some topology functions
* contrib/lisp/org-export.el (org-export-first-sibling-p,
org-export-last-sibling-p, org-export-get-previous-element,
org-export-get-next-element): Add INFO argument. This is necessary
to ignore non-exportable elements or objects.
(org-export--skip-p): Apply signature change.
* testing/lisp/test-org-export.el: Add tests.
* contrib/lisp/org-e-odt.el (org-e-odt-footnote-reference): Apply
signature change.
* contrib/lisp/org-e-latex.el (org-e-latex-footnote-reference,
org-e-latex-headline, org-e-latex-table-cell): Apply signature
change.
* contrib/lisp/org-e-html.el (org-e-html-footnote-reference,
org-e-html-headline): Apply signature change.
* contrib/lisp/org-e-beamer.el (org-e-beamer-export-snippet,
org-e-beamer--format-block): Apply signature change.