1. Valid node checking for LayoutMasterSet done.

1.  Valid node checking for LayoutMasterSet done.
2.  Additional error message provided for missing required child elements of a node.
3.  Removal of elementName from property list; redundant (retrievable via getFObj.getName()).  Adding getName() to FObj so the element so fObj.getName() works.
(Vielen Dank, Simon!)
4.  Moving locator information from FObj to FONode so non-XSL NS elements will also have this information.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@197720 13f79535-47bb-0310-9956-ffa450edef68