Help keep things organized with some section header comments
Beginning of post-specific controls. So far, only overriding the metabox to add our things to.

See #1.
Start of Ajax handling to purge a post's revisions on demand.

See #1.
Handle Ajax-based requests to purge a given post's revisions. Fully functional, though some UI work is needed.

See #1.
Meta box and data storage for post-specific revision quantities.

See #1.
Enforce post-specific revisions quantities.

Also adds a bit of missing inline documentation.

Fixes #1.
Post-specific revisions changes cleanup

* More inline documentation
* Actually purges when requested
* Better error handling

Closes #1