TIFF writer: store 16-bit lookup tables
ImageConverter: ensure that 16-bit lookup tables are preserved
Fix lookup table reading for OME-TIFF files

Without this change, only the first lookup table was returned regardless
of how openBytes was called.
ImageJ exporter: fix lookup table population for 16-bit data

Fixes ticket #11658.
Merge pull request #810 from melissalinkert/ticket-11658

Preserve lookup tables when exporting from ImageJ