Tomo: Warnings on computing flat field

/users/blissadm/local/daiquiri.git/daiquiri/core/components/tomo/imageresource.py:114: RuntimeWarning: divide by zero encountered in true_divide
  d.flat.normalized - d.dark.normalized

This is not useful. This have to be filtered out. Plus using a correction from NaN to 0 how it is now done on tiling correction.