[changeset] clarification to pcolor doc-string

[Francesco Potorti`]

>>>+## @code{shading} modifies an attribute determining the manner by which the
>>>+## face color of each cell is interpolated from the values of @var{c},
>>>+## and the visibility of the cells' edges. By default the attribute is
>>>+## "flat", which renders a single color for each cell's face with the edge
>>>+## visible.
>>
>>The text is correct, apart from the fact that this is not the "flat"
>>attribute, but "interp" or "faceted" (I can not tell which).
>
>The code for pcolor.m appears to be setting each patch to "flat"
>     set (tmp, "facecolor", "flat");
>Why is it you think that is not the case?

This is what I observe with Octave 3.0.1 and gnuplot 4.2.3 on Debian:

## produce a plot with 16 (4x4) squares
octave> pcolor(magic(5))	# edges are visible (black lines)
octave> shading("flat")		# edges become invisible
octave> shading('interp')	# no change
octave> shading('faceted')	# edges become visible again

So apparently the default is "faceted".  I cannot find this as a
property of the plot though, so I can only deduce that by looking at the
plot.