v0.40.0

Adds:

• Popovers are now showable on pageload and are dismissible.
• Popovers now have events for show, shown, hide, and hidden.
• Popovers on hover are documented
• Popover colors can now more easily be overridden using atomic classes
• 96px and 128px spacing units have been added
• .w[x] and .h[x] classes that correspond with our spacing units have been added.

Fixed:

• Email templates now have a pixel-fit, consistent Stack Overflow logo

Removes:

• The s-hero component has been removed