Hide 'Arguments' header since the section isn't implemented; comment out unimplemented sections via PHP
Improve linking related to source code display.

* Remove 'View source code:' label and links
* Add 'View source' link that links downpage to Source section
* Remove ellipsis from link text
* Add ability to collapse expanded source code
* Move link to core.trac for function to be under source code display as 'View on Trac'
* Fix to display link to trac for hooks and classes
Bump CSS version