New syntax recommit, fix cases when pre is not a child of source_section

New syntax highlighter (prism.js) added, old one (SyntaxHighlighter) removed. New html formatter (codeFormat) added. Changes in codeSource to adopt new plugins. Minor changes in css and less files related to new plugins.

Squashed commit of the following:

commit 0c2ac17677d13b68ae428e8e7ad07eab53da8a99
Author: denisprzendzinskis <deniss.przendzinskis@odnoklassniki.ru>
Date:   Fri Dec 13 09:53:14 2013 +0200

    Changes according to review

commit 4f437335e655978bda3cf4c136d6f921180bef2c
Author: denisprzendzinskis <deniss.przendzinskis@odnoklassniki.ru>
Date:   Thu Dec 12 11:49:22 2013 +0200

    Changes according to review

commit 025a017e246efb94468eb49625ae448195a698ae
Author: denisprzendzinskis <deniss.przendzinskis@odnoklassniki.ru>
Date:   Thu Dec 12 11:42:03 2013 +0200

    Changes according to review

commit e87f6de13102b047ab23f1704e9b23461ddf317e
Author: denisprzendzinskis <deniss.przendzinskis@odnoklassniki.ru>
Date:   Wed Dec 11 10:51:30 2013 +0200

    Changes according to review

commit d878597aaead391f6117bd41597b1d76efcc35aa
Author: denisprzendzinskis <deniss.przendzinskis@odnoklassniki.ru>
Date:   Mon Dec 9 14:31:02 2013 +0200

    formatify plugin for HTML code, new syntax highlighter (prism.js) and corresponding changes in codeSource