Quick Sort, REST support, public API, code cleanup

Forgot I never made a new release in the past 4 years. Let's just blame COVID.

• Term order now applies to get_the_terms() output
• Added quick sort controls, currently just title/name
• Rest integration; makes menu_order/term_order an option for orderby
• Public API for registering post types and taxonomies rather than relying on the admin UI

Add sanitizing of POST data

Neglected to sanitize post data when saving post/term order and parent data.

Initial Public Release

v1.0.0

don't need settings_errors() apparently