bug fix for printing DSTs, LDCTracks collections with null pointers to other tracks
bug fix for printing DSTs, LDCTracks collections with null pointers to other tracks


iLCSoft/LCIO,iLCSoft/LCIO,petricm/LCIO,petricm/LCIO,iLCSoft/LCIO,iLCSoft/LCIO,iLCSoft/LCIO,petricm/LCIO,iLCSoft/LCIO,petricm/LCIO,petricm/LCIO,petricm/LCIO