doc: grammarcheck documentation for 4.2 release. * container.txi, contrib.txi, diagperm.txi, errors.txi, external.txi, func.txi, image.txi, nonlin.txi, numbers.txi, plot.txi, quad.txi, sparse.txi, strings.txi, tips.txi, var.txi, vectorize.txi, __dispatch__.cc, cellfun.cc, file-io.cc, gsvd.cc, load-path.cc, regexp.cc, __init_gnuplot__.cc, __osmesa_print__.cc, qr.cc, xzip.cc, ov-classdef.cc, octave_config_info.m, grabcode.m, publish.m, dialog.m, condest.m, normest1.m, mkdir.m, ode23.m, ode45.m, odeplot.m, AbsRel_Norm.m, integrate_adaptive.m, integrate_const.m, integrate_n_steps.m, axis.m, isocaps.m, isocolors.m, isosurface.m, light.m, __calc_isovalue_from_data__.m, __marching_cube__.m, cov.m, median.m: doc: grammarcheck documentation for 4.2 release.

--- a/libinterp/corefcn/file-io.cc	Mon Aug 15 12:46:51 2016 +0200
+++ b/libinterp/corefcn/file-io.cc	Mon Aug 15 10:05:50 2016 -0700
@@ -1453,7 +1453,7 @@
 
 @item @qcode{"ReturnOnError"}
 If set to numerical 1 or true, return normally as soon as an error is
-encountered, such as trying to read a string using @qcode{%f}.
+encountered, such as trying to read a string using @code{%f}.
 If set to 0 or false, return an error and no data.
 
 @item @qcode{"Whitespace"}