added testcase for TixiGetChildElementPaths
added testcase for TixiGetChildElementPaths

DLR-SC/tixi,DLR-SC/tixi,DLR-SC/tixi,melven/tixi,DLR-SC/tixi,melven/tixi,melven/tixi,melven/tixi,DLR-SC/tixi,melven/tixi