org-element: Introduce a new accessor: `org-element-type'

org-element: Introduce a new accessor: `org-element-type'

* EXPERIMENTAL/org-e-ascii.el (org-e-ascii--current-text-width,
  org-e-ascii--build-caption, org-e-ascii--build-title,
  org-e-ascii--describe-links, org-e-ascii-template,
  org-e-ascii-paragraph): Use new accessor
* EXPERIMENTAL/org-e-latex.el (org-e-latex--guess-inputenc): Small
  refactoring.
  (org-e-latex-footnote-reference, org-e-latex-link):  Use new
  accessor.
* contrib/lisp/org-element.el (org-element-type): New function.
  (org-element-map, org-element-parse-elements,
  org-element-interpret-data, org-element-normalize-contents,
  org-element-forward, org-element-unindent-buffer): Use new
  accessor.
* contrib/lisp/org-export.el (org-export-get-inbuffer-options,
  org-export-get-min-level, org-export-data, org-export-skip-p,
  org-export-interpret-p, org-export-expand,
  org-export-expand-include-keyword,
  org-export-prepare-file-contents, org-export-first-sibling-p,
  org-export-resolve-fuzzy-link, org-export-get-ordinal,
  org-export-get-loc, org-export-get-genealogy,
  org-export-get-parent-headline): Use new accessor.