Add first/last & zebra classes to the regions in a zone

Title says enough.

Add first and last classes to the first and last regions in a zone... This takes special consideration as with the push/pull classes (dynamic zones), the regions may be in a different order in source code than they actually appear on page.

Implementing this in the static zones should be easy, and adding to dynamic zones should be possible using the order variable currently set in theme settings.

Also simply add odd/even classes to the regions as well.