Use matrix concatenation for strings, rather than cstrcat(), for clarity and performance. matrix concatenation is ~80% faster than cstrcat(). * doc/interpreter/strings.txi: Document preference for matrix concatenation as opposed to alternatives. * doc/interpreter/geometryimages.m, doc/interpreter/interpimages.m, doc/interpreter/plotimages.m, doc/interpreter/sparseimages.m, doc/interpreter/splineimages.m, scripts/general/genvarname.m, scripts/general/int2str.m, scripts/general/num2str.m, scripts/help/__makeinfo__.m, scripts/help/help.m, scripts/miscellaneous/copyfile.m, scripts/miscellaneous/dir.m, scripts/miscellaneous/edit.m, scripts/miscellaneous/fact.m, scripts/miscellaneous/fullfile.m, scripts/miscellaneous/mkoctfile.m, scripts/miscellaneous/movefile.m, scripts/miscellaneous/perl.m, scripts/miscellaneous/python.m, scripts/miscellaneous/run.m, scripts/miscellaneous/tempdir.m, scripts/miscellaneous/unpack.m, scripts/pkg/private/configure_make.m, scripts/pkg/private/create_pkgadddel.m, scripts/pkg/private/extract_pkg.m, scripts/pkg/private/get_description.m, scripts/pkg/private/get_forge_pkg.m, scripts/pkg/private/getarch.m, scripts/pkg/private/getarchprefix.m, scripts/pkg/private/install.m, scripts/pkg/private/installed_packages.m, scripts/pkg/private/load_packages_and_dependencies.m, scripts/pkg/private/rebuild.m, scripts/pkg/private/repackage.m, scripts/pkg/private/shell.m, scripts/pkg/private/uninstall.m, scripts/plot/private/__go_draw_axes__.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/statistics/tests/z_test.m, scripts/statistics/tests/z_test_2.m, scripts/strings/mat2str.m, scripts/strings/strtok.m, scripts/testfun/__run_test_suite__.m, scripts/testfun/assert.m, scripts/testfun/demo.m, scripts/testfun/speed.m, scripts/testfun/test.m, test/eval-catch.tst, test/io.tst, test/try.tst: Replace cstrcat() with matrix concatenation where possible.

--- a/scripts/general/num2str.m
+++ b/scripts/general/num2str.m
@@ -115,14 +115,14 @@
         fmt = "%3d";
       endif
     endif
-    fmt = cstrcat (deblank (repmat (fmt, 1, columns (x))), "\n");
+    fmt = [deblank(repmat(fmt, 1, columns(x))), "\n"];
     nd = ndims (x);
     tmp = sprintf (fmt, permute (x, [2, 1, 3:nd]));
     retval = strtrim (char (ostrsplit (tmp(1:end-1), "\n")));
   else   # Complex matrix input
     if (nargin == 2)
       if (ischar (arg))
-        fmt = cstrcat (arg, "%-+", arg(2:end), "i");
+        fmt = [arg "%-+" arg(2:end) "i"];
       elseif (isnumeric (arg) && isscalar (arg) && arg >= 0)
         fmt = sprintf ("%%%d.%dg%%-+%d.%dgi", arg+7, arg, arg+7, arg);
       else
@@ -157,7 +157,7 @@
     x = horzcat (real (x), imag (x));
     x = x(idx{:});
 
-    fmt = cstrcat (deblank (repmat (fmt, 1, nc)), "\n");
+    fmt = [deblank(repmat(fmt, 1, nc)), "\n"];
     tmp = sprintf (fmt, permute (x, [2, 1, 3:nd]));
 
     ## Put the "i"'s where they are supposed to be.