Sets up the post object for preview based on the post autosave.

Filters the latest content for preview from the post autosave.

Gets the post revision version.

Returns a post array ready to be inserted into the posts table as a post revision.

Determines which fields of posts are to be saved in revisions.

Filters post thumbnail lookup to set the post thumbnail.

Filters terms lookup to set the post format.

Inserts post data into the posts table as a post revision.

Upgrade the revisions author, add the current post as a revision and set the revisions version to 1

Deletes a revision.