[BUG] problem exporting example block to html

[Nick Dokos <nicholas.dokos@hp.com>]

Exporting the following to html:

--8<---------------cut here---------------start------------->8---

* foo

#+begin_example
#+TITLE: foo
* One

One

* Two

Euler says:

#+begin_latex
\[
\int_0^\infty e^{-x^2} dx = {{\sqrt{\pi}} \over {2}}
\]
#+end_latex
#+end_example
--8<---------------cut here---------------end--------------->8---

deletes the latex section. The problem is that in
org-export-preprocess-string, by the time that we get to
org-export-select-backend-specific-text(), the example has been wrapped in
BEGIN_HTML/END_HTML and the begin_example/end_example have been translated
into <pre>/</pre>. org-export-select-backend-specific-text() then blindly
deletes the latex section since it does not "belong" to the html backend,
not realizing that it is part of a literal example.

There is also a bug in the latex backend: although the example, including
most of the latex section, is wrapped inside a verbatim environment,
the #+end_latex line has been eaten up - I haven't checked by whom.

GNU Emacs 24.0.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.22.0) of 2011-04-13
Org-mode version 7.5 (baseline.265.gcfb05)

Nick