Revision 370494

Following a clarification by the XSL FO SG, space traits are only set on the first and last area generated by an FO, and not on every area anymore.
For details, see: http://wiki.apache.org/xmlgraphics-fop/XslFoSpecificationUncertainties/SpaceTraits

Note: this change brings another issue in column balancing to light. That's the reason for disabling one of the tests. I wasn't able to find a quick fix there.