Misplaced parenthesis in -resample-mm

[cajgfinger]

In ConvertImageND.cxx, the computation of sz is wrong due to a misplaced parenthesis.
It changes the dimension by one in case of small spacing.

The change is small:
sz[i] = static_cast<size_t>((0.5 + sz[i] * m_ImageStack.back()->GetSpacing()[i]) / vox[i]);
should be
sz[i] = static_cast<size_t>((0.5 + sz[i] * m_ImageStack.back()->GetSpacing()[i] / vox[i]));
I can create a PR if needed

[cookpa]

I had the same problem, it becomes a serious issue for small animal images. I made a PR #16