BUG: Address randomly failing morphological filter with temp var
BUG: Address randomly failing morphological filter with temp var

Following design pattern in other systems to store morphological output
in a temp variable prior to assigning to input var.   Shouldn't matter,
but perhaps optimizations are causing trouble and this avoids them.

aylward/ITKTubeTK,thewtex/TubeTK,aylward/ITKTubeTK,KitwareMedical/ITKTubeTK,thewtex/TubeTK,KitwareMedical/ITKTubeTK,aylward/ITKTubeTK,thewtex/TubeTK,KitwareMedical/ITKTubeTK,thewtex/TubeTK,KitwareMedical/ITKTubeTK,aylward/ITKTubeTK