compare_float() was an ad hoc max error logger with optional debug
logging.
Now that we have rgb_diff_stat, we can get the same statistics and more
with less code. It looks like we would lose the pixel index x, but that
can be recovered from the dump file line number.
This patch takes care to keep the test condition exactly the same as it
was before. The statistics print-out has more details now.
The recorded dump position is the foreground color as that varies while
the background color is constant.
An example Octave function is included to show how to visualize the
rgb_diff_stat dump.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
