loads images that represent a 3D stack as a sequence
of slice with one image file per slice, such as created by Stephan
Preibisch's Multi-view fusion plugin. It is constructed with the pattern of
the image filenames. Then, to laod the image for a given
, its TODO timepoint? index?, channel, and slice
indices are filled into the template to get the slice filenames.
is used for exporting spim sequences to hdf5. Only the
implemented because this is the only method required for exporting to hdf5.