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/test/try.tst
+++ b/test/try.tst
@@ -71,7 +71,7 @@
 
 %!function ms = mangle (s)
 %!  ## Wrap angle brackets around S.
-%!  ms = cstrcat ("<", s, ">");
+%!  ms = ["<" s ">"];
 %!endfunction
 %!test
 %! try
@@ -121,7 +121,7 @@
 %!     a;
 %!     error ("Shoudn't get here");
 %!   catch
-%!     error (cstrcat ("rethrow: ", lasterr));
+%!     error (["rethrow: " lasterr]);
 %!   end_try_catch
 %! catch
 %!   assert (lasterr()(1:22), "rethrow: 'a' undefined");