Allow to not strip HTML tags in the generated TOC.

Introduce a new option to toggle this behavior: stripHtmlInToc, default
to false.

Fixes #6.
Support steps in the backward direction.

Thanks to @mcapelle and @cexbrayat.
Remove useless call to .show() in steps.
Do not display pagination when printing.

Fixes #7.
Allow using left and right clicks to navigate.
Allow using the mouse wheel to navigate.
Fix syntax highlighting for the toc example.
Bump version to 0.3.0.
Merge branch 'master' into gh-pages