Modified Files:
Added toXML() methods.
ox/src/java/de/fhworms/ztt/ox/campusdatarepository/StudentCatalog.java
ox/src/java/de/fhworms/ztt/ox/examrepository/ProblemCatalog.java
ox/src_test/java/unit/de/fhworms/ztt/ox/campusdatarepository/StudentCatalogTest.java
ox/src_test/java/unit/de/fhworms/ztt/ox/examrepository/ProblemCatalogTest.java