Implement whitespace management extension using fo:multi-switch
Patch from 13/10/28 by Seifeddine Dridi, applied with some modifications.


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_WhitespaceManagement@1539809 13f79535-47bb-0310-9956-ffa450edef68