PHPdoc effort for collective file level documentation

[darkdragon]

PHPdoc style documentation for the following files:

File and Global Levels

1. version.php
2. vars.php

File Level

1. registration-functions.php
2. rss-functions.php
3. streams.php
4. gettext.php

There needs to be some cleanup on the other external library file level documentation. I've found that specifying just the package for external libraries can be confusing to visitors looking at phpdocumentor sites.

I think using @package External with the @subpackage as the library name is a better for the user experience. A new user would immediately be able to see in a phpdocumentor site that the libraries belong to an outside source.

Kses was not updated, since it is fairly well integrated into WordPress therefore needs documentation.

Patch does not clean up other external files phpdoc documentation.

Based off of r6542

(In [6554]) Some file level phpdoc from darkdragon. fixes #5572