doc: Periodic grammarcheck of documentation. * doc/interpreter/contrib.txi, doc/interpreter/expr.txi, doc/interpreter/func.txi, doc/interpreter/linalg.txi, doc/interpreter/plot.txi, libinterp/corefcn/data.cc, libinterp/corefcn/debug.cc, libinterp/corefcn/graphics.cc, libinterp/corefcn/help.cc, libinterp/corefcn/load-save.cc, libinterp/corefcn/profiler.cc, libinterp/corefcn/syscalls.cc, libinterp/corefcn/utils.cc, libinterp/corefcn/variables.cc, libinterp/dldfcn/__init_fltk__.cc, scripts/general/deal.m, scripts/help/__gripe_missing_component__.m, scripts/miscellaneous/desktop.m, scripts/pkg/private/default_prefix.m, scripts/plot/appearance/__getlegenddata__.m, scripts/plot/util/pan.m, scripts/plot/util/rotate.m, scripts/plot/util/rotate3d.m, scripts/plot/util/zoom.m, scripts/signal/periodogram.m, scripts/specfun/factor.m, scripts/specfun/primes.m, scripts/statistics/base/lscov.m, scripts/testfun/private/compare_plot_demos.m, scripts/testfun/private/dump_demos.m, scripts/testfun/private/html_compare_plot_demos.m, scripts/testfun/test.m: Periodic grammarcheck of documentation.

--- a/scripts/specfun/factor.m	Mon Sep 22 20:25:21 2014 -0700
+++ b/scripts/specfun/factor.m	Mon Sep 22 20:46:54 2014 -0700
@@ -28,7 +28,7 @@
 ## With two output arguments, return the unique prime factors @var{pf} and
 ## their multiplicities.  That is, @code{prod (@var{pf} .^ @var{n}) == @var{q}}.
 ## 
-## Implementation Note: The input @var{q} must be less than than
+## Implementation Note: The input @var{q} must be less than
 ## @code{bitmax} (9.0072e+15) in order to factor correctly.
 ## @seealso{gcd, lcm, isprime, primes}
 ## @end deftypefn