org-element: Verse blocks now contain objects
* contrib/lisp/org-element.el (org-element-verse-block-parser): Verse
blocks now contain objects.
(org-element-verse-block-interpreter, org-element-current-element):
Apply changes to verse blocks.
(org-element-secondary-value-alist): Remove verse blocks from elements
with a secondary string.
* contrib/lisp/org-e-odt.el (org-e-odt-verse-block): Apply changes to
verse blocks.
* contrib/lisp/org-e-latex.el (org-e-latex-verse-block): Apply changes
to verse blocks.
* contrib/lisp/org-e-html.el (org-e-html-verse-block): Apply changes
to verse blocks.
* contrib/lisp/org-e-ascii.el (org-e-ascii-verse-block): Apply changes
to verse blocks.
* testing/lisp/test-org-element.el: Add tests.