attempt to fix testSymmetry for GizmoMFV
test/testSymmetry.c
wouldn't compile for the current version of GizmoMFV, it was looking for primitive
structs in the part
sturct.
Furthermore, the GizmoMFV specific particle comparisons routinely raised FPE errors when overflows, infinities, and NaNs were read in from the particle structs as floats. I re-wrote those checks to attempt a memcmp
first, and if that failed, we then do a check for precision.