doc: Improve documentation for 2-D plot functions * doc/interpreter/plot.txi: Rewrite documentation around get/set. * libinterp/interpfcn/graphics.cc(Fget, Fset): Add seealso links. Add additional calling forms for get(). * scripts/plot/bar.m, scripts/plot/barh.m, scripts/plot/comet.m, scripts/plot/comet3.m, scripts/plot/contour.m, scripts/plot/contour3.m, scripts/plot/contourc.m, scripts/plot/contourf.m, scripts/plot/errorbar.m, scripts/plot/gca.m, scripts/plot/gcf.m, scripts/plot/gco.m, scripts/plot/ishghandle.m, scripts/plot/loglogerr.m, scripts/plot/pareto.m, scripts/plot/pcolor.m, scripts/plot/pie.m, scripts/plot/pie3.m, scripts/plot/plotmatrix.m, scripts/plot/plotyy.m, scripts/plot/polar.m, scripts/plot/quiver.m, scripts/plot/quiver3.m, scripts/plot/rose.m, scripts/plot/scatter.m, scripts/plot/semilogxerr.m, scripts/plot/semilogyerr.m, scripts/plot/sombrero.m, scripts/plot/stairs.m, scripts/plot/stem.m, scripts/plot/stem3.m: Improve docstrings.

--- a/scripts/plot/quiver.m
+++ b/scripts/plot/quiver.m
@@ -41,7 +41,7 @@
 ## in a similar manner to the line styles used with the @code{plot} command.
 ## If a marker is specified then markers at the grid points of the vectors are
 ## printed rather than arrows.  If the argument "filled" is given then the
-## markers as filled.
+## markers are drawn filled.
 ##
 ## The optional return value @var{h} is a graphics handle to a quiver object.
 ## A quiver object regroups the components of the quiver plot (body, arrow,
@@ -55,7 +55,7 @@
 ## @end group
 ## @end example
 ##
-## @seealso{plot}
+## @seealso{quiver3, feather, plot}
 ## @end deftypefn
 
 function retval = quiver (varargin)