Fix issue #33 :
- add a test to verify the exportation of relative reference path in XML file
- fix the issue in vtkXMLUtilities module
491 Unit tests OK, in 181,88s
Fix issue #33 in the VBAToolkit XML project file
Merge pull request #36 from jpimbert/Issue#33-RelativeReferencePathInXML

Issue#33 relative reference path in xml