Wrap all the reports in a single html file

[harendra-kumar]

Depending on the options a lot many reports/graphs can be generated by bench-show in one go. It will be convenient to have an option to wrap the output in a single html file. We can also have an option to automatically open the html file in the browser. Something like:

--html
--open-html

All the reports/graphs can be shown inline in a single page instead of having to navigate multiple links.