ob-R.el: fix a bug when a :var is propertized text

* lisp/ob-R.el (org-babel-R-assign-elisp): Strip text properties from
strings.

Before this change, babel would try to format propertized strings
using elisp read syntax.  The upshot is that evaluating the following
code block would give an error (in R, not emacs), since the “bar” in
foo-ex gets text properties via font lock:

| #+name: foo-ex
| #+begin_example
| bar
| #+end_example
|
| #+name: foo
| #+begin_src R :var foo=foo-ex
|   foo
| #+end_src
ob-R.el: Improve the capturing of output-type results in sessions.

* lisp/ob-R.el (org-babel-R-evaluate-session): Improve the capturing
of R output.

This uses a built-in facility of R to write the output to a file,
rather than trying to capture it in an emacs buffer using ESS (a
process by which the output can get mixed with other irrelevant text,
such as R command prompts).
org-element: Accept missing final newlines in block values

* lisp/org-element.el (org-element-comment-block-interpreter,
  org-element-example-block-interpreter,
  org-element-src-block-interpreter): Handle values with missing final
  newline, e.g., when built by the user.

* testing/lisp/test-org-element.el (test-org-element/comment-block-interpreter,
  test-org-element/example-block-interpreter,
  test-org-element/src-block-interpreter): Add tests

Thanks to Thorsten Jolitz for suggesting the idea.
http://permalink.gmane.org/gmane.emacs.orgmode/89602
Fix bug associated with setting image size via ATTR.

* lisp/org.el (org-display-inline-images): This change is necessary to
  make ATTR work.  Removed unnecessary save-match-data forms.
Revert "ob-R.el: Improve the capturing of output-type results in sessions."

This reverts commit b51746332dca87a35c387b2db0bb678b4c24a4da.
ox-org: OPTIONS keyword belong to the template

* lisp/ox-org.el (org-org-keyword): Do not handle OPTIONS keywords
  since those are handled in the template.
(org-org-template): Handle OPTIONS keyword.

As a consequence, OPTIONS keyword do not appear anymore when doing
a body-only export.

Thanks to Thorsten Jolitz for suggesting the idea.
http://permalink.gmane.org/gmane.emacs.orgmode/89633
ox-org: Update wrt `org-element-block-name-alist' change

* lisp/ox-org.el (org-org-keyword): Do not check for keywords
  targeting other export back-ends since
  `org-element-block-name-alist' doesn't contain such information
  anymore.
Allow a plist as the optional 2nd argument to org-email-link-description
Document that org-get-heading is useful when using org-map-entries
Mention org-no-properties too.
Document org-no-properties
FIXME: keep org-mairix-mutt-display-command output in buffer for debug