org-element: Remove some unneeded element properties

org-element: Remove some unneeded element properties

* contrib/lisp/org-element.el (org-element-center-block-parser,
  org-element-quote-block-parser,
  org-element-quote-block-interpreter,
  org-element-special-block-parser,
  org-element-special-block-interpreter,
  org-element-babel-call-interpreter,
  org-element-comment-block-parser,
  org-element-export-block-interpreter,
  org-element-src-block-interpreter,
  org-element-example-block-interpreter): Use standard case for Org
  syntax.
(org-element-inlinetask-parser): Remove `:raw-value' property.
(org-element-headline-interpreter,
org-element-inlinetask-interpreter): Rely on `:title' property instead
of `:raw-value'.
(org-element-item-parser): Remove `:raw-tag' property.
(org-element-item-interpreter): Do not use `:raw-tag' anymore.  Rely
on `:tag' instead.
(org-element-verse-block-parser): Remove `:raw-value' property.  Use
standard case for Org syntax, too.
(org-element-verse-block-interpreter): Rely on `:value' instead of
`:raw-value'.
(org-element-footnote-reference-parser): Remove `:raw-definition'
value.
(org-element-footnote-reference-interpreter): Use `:inline-definition'
property, when non-nil, instead of `:raw-definition'.
(org-element-radio-target-parser): Rename `:raw-value' into `:value'.

Most raw values don't add worthy information to an element, since they
can be retrieved with an interpretation of the secondary string they
represent.