Example Lines/Fixed Width Areas

[CarlColglazier]

Babel often produces output like the following:

#+HEADER: :exports both :results output :cache yes
#+BEGIN_SRC C 
  #include <stdlib.h>
  #include <stdio.h>

  int main() {
    printf("Hello, World!\n");
    return 0;
  }
#+END_SRC

#+RESULTS[89f50bc6df96e44b1fd5800817c76a086b3c7a87]:
: Hello, World!

The results section should compile to

<pre class="example">
Hello, World!
</pre>

Org-mode describes these lines as example lines which produce fixed width areas.

This pull request adds support for fixed width areas. Note that example lines can come directly after paragraph lines. I have added several tests to ensure that the behavior is as expected.

[curiouslychase]

LGTM. Thanks for continuing to contribute!

The test failures are coveralls repotoken failures, I've fixed that so hopefully it shouldn't give anyone problems in the future.