Add Print icon on the header

[S-mardii]

To explicitly allow the user to print the page, the team requested to add the icon on the header of the webpage next to the other social icons.

This would make the change as following:

• In Open Development Theme Options page, add a new checkbox field called "Show print icon" under a new section "Header"
• Include new class in the stylesheet
• Display the icon on the header of the file if the option is checked in the Theme Options page.