Revert "ChannelFiller: ensure color table is stripped"

This reverts commit fc43616193b73808501b61ed386236c70c743220.

We were being overly-aggressive in stripping color tables. If a color
table is available, we should return it even if we don't explicitly
expand it via the ChannelFiller.
FormatTools: add getNonPlanarAxisPosition method

Added a convenience method to look up the axis position, given a
corresponding plane index.
TIFFFormat: parse IJ1 color table

ImageJ 1.x can write 8-bit lookup tables in the TIFF ImageJ 1.x comment.
These are not properly read when retrieved from the IFD as a String.
They need to be parsed by reading the metadata tags and determining the
actual offsets and lengths.

We now parse and use the IJ 1.x color table if needed.

Closes #202

NB: See also #203 for future plans