Update ruby-kramdown to 0.13.6.

commit 40e6cde2d3e1a4f9f6bc14a243b22b4ae3311ca2
Author: Thomas Leitner <t_leitner@gmx.at>
Date:   Wed May 9 19:53:47 2012 +0200

    Updated release notes and version number

doc/news/release_0_13_6.page
doc/sidebar.template
lib/kramdown/version.rb
man/man1/kramdown.1.erb

commit 7f66dca331f78d84ef22c489c755360b304cb41f
Author: Thomas Leitner <t_leitner@gmx.at>
Date:   Tue May 8 21:20:46 2012 +0200

    Fixed bug RF#29557: Parsing fails with lists with empty list item

    If a list item is completely empty, it needs to be handled specially,
    which is done now.

lib/kramdown/converter/kramdown.rb
lib/kramdown/parser/kramdown/list.rb
test/testcases/block/08_list/special_cases.html
test/testcases/block/08_list/special_cases.text

commit ac00ea8ea590ece6c7a6c53b30920114f349b79b
Author: Thomas Leitner <t_leitner@gmx.at>
Date:   Tue May 8 20:02:43 2012 +0200

    Fixed problem with CDATA section in non-XHTML pages

    The HTML parser does not parse CDATA in script tags and
    therefore the CDATA tags were displayed in MathJax output.
    By commenting out the CDATA tags (with LaTeX comment syntax)
    we avoid this problem.

lib/kramdown/converter/html.rb
lib/kramdown/parser/html.rb
test/testcases/block/15_math/normal.html


(taca)