1. Implemented validateChildNode() for fo:simple-page-master. This may cause some...

1. Implemented validateChildNode() for fo:simple-page-master.  This may cause some stress with the user community--as any declared fo:region-xxxx children must follow a specific ordering.

2. Modified several of our sample and test FO files to be compliant with the XSL spec with respect to the change above.

3. @todo's added to FO's still missing validateChildNode()

4. New FONode missingPropertyError() method created, for the major cases where missing properties should halt processing.

5. Various cleanup in our layout-master-set and region classes, including the removal of error checks that are no longer needed due to validateChildNode() being implemented.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@197889 13f79535-47bb-0310-9956-ffa450edef68