Changes to doxygen build and robust.sql_in

* Removes from the build the patch that updates the CSS file and relocates those css changes with a few new ones to a new madlib_extra.css file. This is the method recommended in the doxygen guide. 
* The standard doxygen HTML header was generated, checked in, and edited to add keywords to hopefully improve Internet search hits. 
* Links in the header point to previous versions of the MADlib user doc on madlib.net.
* Updates to robust.sql_in are included because they depend on some of these changes.