REFAC: defaultDt should be used instead of dt for pbd, changed cloth topology

Examples/MultipleScenes/multipleScenes.cpp

Examples/PBD/PBDCloth/pbdClothExample.cpp

...ionMultipleObjects/PBDCollisionMultipleObjectsExample.cpp

...BD/PBDCollisionOneObject/PBDCollisionOneObjectExample.cpp

Examples/PBD/PBDFluids/PBDFluidsExample.cpp

Examples/PBD/PBDString/pbdStringExample.cpp