Cellomics: fix handling of channels and analysis images

Channels are now detected correctly.  If the original file passed to
setId is a "d" channel (i.e. original image), then only "d" channels
will be included in the used file list.  If the file passed to setId is
an "o" channel (i.e. analysis results), then only "o" channels will be
included in the used file list.

Fixes #11148.
Zeiss CZI: fix Z size calculation

For linescans in particular, the Z size is stored in the 'size' field,
not the 'start' attribute.

Fixes ticket #11513.