[GRASS5] r.in.tiff changes

[Eric G. Miller]

I've made some modifications to r.in.tiff to hopefully make it a bit
more useable.  I completely removed all of the color reduction
code and am just forcing all RGB TIFF's into respective band files.
Since, r.in.tiff was completely unusable for me here, due to the
ridiculous stack allocation for the color reduction code, I would
propose that folks grab it and build it, and if stable we push it to
the release branch.  

There have been alot of complaints about r.in.tiff, and given both the
extra work required to get r.in.gdal up and running and the ubiquity of
TIFF files for imagery,  I think it's a worthy thing to get it working
better for folks.  So, I need your help testing it!

I've tried it with gray, palette and RGB without trouble (with and
without a world file).  I haven't tested the monochrome and less than 8
bits per pixel code, but that's mostly unchanged...

-- 
Eric G. Miller <egm2 at jps.net>