Add the missing CSS classes for different sections in the file page template

The api-file-page.tpl.php does not provide classes for styling the different sections in the page. The template supports the following sections

* - $alternatives: List of alternate versions (branches) of this file.
 * - $documentation: Documentation from the comment header of the file.
 * - $see: See also documentation.
 * - $deprecated: Deprecated documentation.
 * - $namespace: Name of the namespace for this function, if any.
 * - $objects: List of functions, classes, etc. defined in the file.
 * - $call_links: Links to calling functions (for theme templates).
 * - $code: Source code for the file.
 * - $related_topics: List of related groups/topics.
 * - $defined: Location of the file.

Classes for 'code' and 'defined' are defined in the css file and also used in other templates.

It would be good to get a div wrapper with the appropriate classes for all these sections to allow for styling without overriding the template.