* Makes the header/sidebar component embeddable on other WooCommerce pages.
* Some mobile CSS fixes to make sure the header bar displays properly on smaller screensizes.
* Refactor notices and pull out success message from the panel
* Handle positioning of screen options, update message handling, css fixes and header height increase to match mockups, some code cleanup
* Only enable the header embed on normal/classic WooCommerce pages, and provide a method for plugins to opt-in.
This change also builds nicer breadcrumbs for pages.
* Code cleanup and consistent naming.
* Some spacing cleanup. Also updated the page title method to correctly set page titles in PHP for classic WC pages
Justin Shreve
Kelly Dwan