Add an API for section groups

[mgburns]

From WP.org (http://wordpress.org/support/topic/can-posts-be-added-to-sections-programmatically?replies=1):

We have a large site with multiple Custom Post Types. Since child pages are frequently different types, and can appear in multiple locations, we are using the Posts 2 Posts plugin, rather than parent-child hierarchy, to link posts.

I am trying to do things programmatically, so that section editors will be able to create their own pages without admins having to add every post to section groups.

Are there a functions to:

1. determine which section(s) a user is a member of?
2. determine which section(s) a post is in?
3. add a post to a section group?