doc: Replace "non-zero" with "nonzero" to match existing usage. Replace all occurrences in both documentation and code comments. * doc/interpreter/contrib.txi, doc/interpreter/diagperm.txi, doc/interpreter/external.txi, doc/interpreter/sparse.txi, doc/interpreter/stmt.txi, doc/interpreter/testfun.txi, doc/refcard/refcard.tex, examples/mysparse.c, libinterp/corefcn/balance.cc, libinterp/corefcn/cellfun.cc, libinterp/corefcn/data.cc, libinterp/corefcn/filter.cc, libinterp/corefcn/find.cc, libinterp/corefcn/kron.cc, libinterp/corefcn/ls-mat5.cc, libinterp/corefcn/luinc.cc, libinterp/corefcn/mappers.cc, libinterp/corefcn/oct-fstrm.cc, libinterp/corefcn/oct-fstrm.h, libinterp/corefcn/oct-iostrm.cc, libinterp/corefcn/oct-iostrm.h, libinterp/corefcn/oct-stdstrm.h, libinterp/corefcn/oct-strstrm.h, libinterp/corefcn/spparms.cc, libinterp/corefcn/toplev.cc, libinterp/corefcn/utils.cc, libinterp/dldfcn/symrcm.cc, libinterp/octave-value/ov-bool-mat.cc, liboctave/array/CSparse.cc, liboctave/array/Sparse.cc, liboctave/array/Sparse.h, liboctave/array/dSparse.cc, liboctave/numeric/randmtzig.c, liboctave/operators/Sparse-op-defs.h, scripts/help/get_first_help_sentence.m, scripts/miscellaneous/edit.m, scripts/plot/draw/pie.m, scripts/plot/draw/pie3.m, scripts/sparse/colperm.m, scripts/sparse/nonzeros.m, scripts/sparse/spdiags.m, scripts/sparse/spfun.m, scripts/sparse/spones.m, scripts/sparse/sprand.m, scripts/sparse/sprandn.m, scripts/sparse/sprandsym.m, scripts/sparse/spstats.m, scripts/sparse/svds.m, scripts/special-matrix/gallery.m, scripts/statistics/base/moment.m, scripts/statistics/tests/cor_test.m: Replace "non-zero" with "nonzero" to match existing usage.

--- a/doc/interpreter/testfun.txi	Sun Jun 08 16:36:54 2014 -0700
+++ b/doc/interpreter/testfun.txi	Sun Jun 08 17:59:59 2014 -0700
@@ -297,14 +297,14 @@
 @group
 function output = must_be_zero (@var{input})
   if (@var{input} != 0)
-    error ("Non-zero input!")
+    error ("Nonzero input!")
   endif
   output = input;
 endfunction
 
 %!fail ("must_be_zero (1)");
 %!assert (must_be_zero (0), 0);
-%!error <Non-zero> must_be_zero (1);
+%!error <Nonzero> must_be_zero (1);
 %!xtest error ("This code generates an error");
 @end group
 @end example
@@ -320,7 +320,7 @@
 >>>>> /path/to/must_be_zero.m
   ***** fail ("must_be_zero (1)");
   ***** assert (must_be_zero (0), 0);
-  ***** error <Non-zero> must_be_zero (1);
+  ***** error <Nonzero> must_be_zero (1);
   ***** xtest error ("This code generates an error");
 !!!!! known failure
 This code generates an error