Add sectioning to body classes, include main-header function
Move logic to functions.php, do markup here
Separate main-header function out into include file
Remove testing detritus
Formatting cleanup for WP code standards
Use get_post() rather than the global $post object
Use get_permalink() and get_home_url() to build classes

Reworks the logic to use get_permalink() as a base for determining
depth, section, sub-section, and page from an individual page view.
Spacing, formatting
No need to check global post when looping categories on is_singular
Place filter call above function for readability
Add docs to speckled body classes
Code formatting for spine_section_meta
get_page() has been deprecated in favor of get_post()
Only parse ancestor data when ancestors are known to exist

Removes the requirement for the global $post object
Move includes of other functionality to top of functions.php

Improves readability
Remove closing PHP tag
Tweak spacing for readability
Refactor handling of sup and sub around missing page_for_posts

WordPress has no page assigned for posts by default, so we'll need
to work around that for determining proper sub and sub headings.
Escape home_url as a link
Reorg documentation around spine_get_main_header in header template