Rework XML import: * handle root and object node separately * prepare for other node classes * root nodes are only allowed at the very top of the XML hierarchy * there should be a single root node
Rework XML import:
* handle root and object node separately
* prepare for other node classes
* root nodes are only allowed at the very top of the XML hierarchy
* there should be a single root node

This commit was SVN r1680.

shekkbuilder/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc