org-element: Define new objects (bold, code, italic, ...)

org-element: Define new objects (bold, code, italic, ...)

* contrib/lisp/org-e-ascii.el (org-e-ascii-option-alist): Fix typo.
(org-e-ascii-bold, org-e-ascii-code, org-e-ascii-strike-through,
org-e-ascii-underline): New functions.
(org-e-ascii-emphasis): Remove function.
* contrib/lisp/org-e-html.el (org-e-html-text-markup-alist): Variable
  renamed from `org-e-html-emphasis-alist'.  Change value type.
(org-e-html-bold, org-e-html-italic, org-e-html-strike-through,
org-e-html-underline): New functions.
(org-e-html-verbatim): Update function.
(org-e-html-emphasis): Remove function.
* contrib/lisp/org-e-latex.el (org-e-latex-text-markup-alist):
  Variable renamed from `org-e-latex-emphasis-alist'.  Change value
  type.
(org-e-latex-center-block): Fix docstring.
(org-e-latex--text-markup, org-e-latex-bold, org-e-latex-code,
org-e-latex-italic, org-e-latex-strike-through,
org-e-latex-underline): New functions.
(org-e-latex-verbatim): Update function.
(org-e-latex-emphasis): Remove function.
* contrib/lisp/org-e-odt.el (org-e-odt-bold, org-e-odt-code,
  org-e-odt-italic, org-e-odt-strike-through, org-e-odt-underline):
  New functions.
(org-e-odt-verbatim): Update function.
(org-e-odt-center-block): Fix docstring.
(org-e-odt-emphasis): Remove function.
* contrib/lisp/org-element.el (org-element-bold-parser):
(org-element-bold-interpreter, org-element-code-parser,
org-element-code-interpreter, org-element-italic-parser,
org-element-italic-interpreter, org-element-strike-through-parser,
org-element-strike-through-interpreter, org-element-underline-parser,
org-element-underline-interpreter): New functions.
(org-element-emphasis-parser, org-element-emphasis-interpreter):
Remove functions.
(org-element-verbatim-parser, org-element-verbatim-interpreter,
org-element-text-markup-successor): Update function.
(org-element-object-successor-alist): Add associations for new object
types.
(org-element-recursive-objects): Add `bold', `italic',
`strike-through' and `underline' as recursive types.
(org-element-object-restrictions): Add restrictions for new recursive
object types.
* contrib/lisp/org-export.el (org-export-filters-alist): Add filters
  for new object types.
(org-export-with-todo-keywords): Add missing keywords.
(org-export-filter-center-block-functions,
org-export-filter-drawer-functions,
org-export-filter-dynamic-block-functions,
org-export-filter-headline-functions,
org-export-filter-inlinetask-functions,
org-export-filter-plain-list-functions,
org-export-filter-item-functions, org-export-filter-comment-functions,
org-export-filter-comment-block-functions,
org-export-filter-example-block-functions,
org-export-filter-export-block-functions,
org-export-filter-fixed-width-functions,
org-export-filter-footnote-definition-functions,
org-export-filter-horizontal-rule-functions,
org-export-filter-keyword-functions,
org-export-filter-latex-environment-functions,
org-export-filter-babel-call-functions,
org-export-filter-paragraph-functions,
org-export-filter-property-drawer-functions,
org-export-filter-quote-section-functions,
org-export-filter-quote-block-functions,
org-export-filter-section-functions,
org-export-filter-special-block-functions,
org-export-filter-src-block-functions,
org-export-filter-table-functions,
org-export-filter-table-cell-functions,
org-export-filter-table-row-functions,
org-export-filter-verse-block-functions,
org-export-filter-entity-functions,
org-export-filter-export-snippet-functions,
org-export-filter-footnote-reference-functions,
org-export-filter-inline-babel-call-functions,
org-export-filter-inline-src-block-functions,
org-export-filter-latex-fragment-functions,
org-export-filter-line-break-functions,
org-export-filter-link-functions, org-export-filter-macro-functions,
org-export-filter-radio-target-functions,
org-export-filter-statistics-cookie-functions,
org-export-filter-subscript-functions,
org-export-filter-superscript-functions,
org-export-filter-target-functions,
org-export-filter-time-stamp-functions,
org-export-filter-verbatim-functions): Fix docstring.
(org-export-filter-bold-functions, org-export-filter-code-functions,
org-export-filter-italic-functions,
org-export-filter-strike-through-functions,
org-export-filter-underline-functions): New variables.
(org-export-filter-emphasis-functions): Remove variable.
* testing/lisp/test-org-element.el: Add tests.