maint: Use new C++ archetype in more files. Place input validation first in files. Move declaration of retval down in function to be closer to point of usage. Eliminate else clause after if () error. Use "return ovl()" where it makes sense. * find.cc, gammainc.cc, gcd.cc, getgrent.cc, getpwent.cc, givens.cc, graphics.cc, help.cc, hess.cc, hex2num.cc, input.cc, kron.cc, load-path.cc, load-save.cc, lookup.cc, mappers.cc, matrix_type.cc, mgorth.cc, nproc.cc, ordschur.cc, pager.cc, pinv.cc, pr-output.cc, profiler.cc, psi.cc, quad.cc, rcond.cc, regexp.cc, schur.cc, sighandlers.cc, sparse.cc, str2double.cc, strfind.cc, strfns.cc, sub2ind.cc, svd.cc, sylvester.cc, symtab.cc, syscalls.cc, sysdep.cc, time.cc, toplev.cc, tril.cc, tsearch.cc, typecast.cc, urlwrite.cc, utils.cc, variables.cc, __delaunayn__.cc, __eigs__.cc, __glpk__.cc, __magick_read__.cc, __osmesa_print__.cc, __voronoi__.cc, amd.cc, audiodevinfo.cc, audioread.cc, chol.cc, colamd.cc, dmperm.cc, fftw.cc, qr.cc, symbfact.cc, symrcm.cc, ov-bool-mat.cc, ov-cell.cc, ov-class.cc, ov-classdef.cc, ov-fcn-handle.cc, ov-fcn-inline.cc, ov-flt-re-mat.cc, ov-java.cc, ov-null-mat.cc, ov-oncleanup.cc, ov-re-mat.cc, ov-struct.cc, ov-typeinfo.cc, ov-usr-fcn.cc, ov.cc, octave.cc: Use new C++ archetype in more files.

--- a/libinterp/dldfcn/symrcm.cc	Fri Dec 18 16:22:53 2015 -0500
+++ b/libinterp/dldfcn/symrcm.cc	Fri Dec 18 15:37:22 2015 -0800
@@ -437,11 +437,11 @@
 @seealso{colperm, colamd, symamd}\n\
 @end deftypefn")
 {
-  octave_value retval;
-
   if (args.length () != 1)
     print_usage ();
 
+  octave_value retval;
+
   octave_value arg = args(0);
 
   // the parameter of the matrix is converted into a sparse matrix
@@ -475,7 +475,7 @@
     }
 
   if (nr == 0 && nc == 0)
-    return octave_value (NDArray (dim_vector (1, 0)));
+    return ovl (NDArray (dim_vector (1, 0)));
 
   // sizes of the heaps
   octave_idx_type s = 0;
@@ -504,7 +504,8 @@
     {
       for (octave_idx_type i = 0; i < N; i++)
         P(i) = i;
-      return octave_value (P);
+
+      return ovl (P);
     }
 
   // a heap for the a node's neighbors. The number of neighbors is
@@ -693,5 +694,5 @@
     std::swap (P.elem (i), P.elem (j));
 
   // increment all indices, since Octave is not C
-  return octave_value (P+1);
+  return ovl (P+1);
 }