Replace division in CrankNicholson.cpp with inverse multiplication
Replace division in CrankNicholson.cpp with inverse multiplication

Experimenting with changes.

Crank seems to be fixed

tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem,tobeycarman/dvm-dos-tem