* contrib/lisp/org-e-ascii.el (org-e-ascii--build-title,
org-e-ascii--build-caption, org-e-ascii--list-listings,
org-e-ascii--list-tables, org-e-ascii--describe-links,
org-e-ascii-template--document-title, org-e-ascii-dynamic-block,
org-e-ascii-inlinetask, org-e-ascii-item, org-e-ascii-link,
org-e-ascii-quote-section, org-e-ascii--table-cell-width): Do not
provide back-end symbol.
* contrib/lisp/org-e-html.el (org-e-html--caption/label-string,
org-e-html-footnote-section, org-e-html-template,
org-e-html-dynamic-block, org-e-html-format-headline--wrap,
org-e-html-headline, org-e-html-item, org-e-html-link,
org-e-html-time-stamp): Do not provide back-end symbol.
* contrib/lisp/org-e-latex.el (org-e-latex--caption/label-string,
org-e-latex-template, org-e-latex-dynamic-block,
org-e-latex-footnote-reference, org-e-latex-headline,
org-e-latex-inlinetask, org-e-latex-item, org-e-latex-link,
org-e-latex-src-block): Do not provide back-end symbol.
* contrib/lisp/org-e-odt.el (org-e-odt-format-preamble,
org-e-odt-format-label, org-e-odt-write-manifest-file,
org-e-odt--caption/label-string, org-e-odt-dynamic-block,
org-e-odt-format-headline--wrap, org-e-odt-headline, org-e-odt-item,
org-e-odt-latex-environment, org-e-odt-link, org-e-odt-src-block,
org-e-odt-time-stamp): Do not provide back-end symbol.
* contrib/lisp/org-export.el (org-export-get-environment): Provide
back-end symbol under `:back-end' property.
(org-export-collect-tree-properties, org-export-data,
org-export-filter-verbatim-functions, org-export-install-filters,
org-export-as, org-export-expand-macro,
org-export-filter-apply-functions, org-export-secondary-string):
Remove back-end references.
* testing/lisp/test-org-export.el: Update tests.
Back-end can be found in communication channel with (plist-get
info :back-end). Hence back-ends do not have to hard-code their name
in any transcoder. It will allow to derive a back-end from another
one.
