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/corefcn/quad.cc	Fri Dec 18 16:22:53 2015 -0500
+++ b/libinterp/corefcn/quad.cc	Fri Dec 18 15:37:22 2015 -0800
@@ -180,9 +180,10 @@
 @seealso{quad_options, quadv, quadl, quadgk, quadcc, trapz, dblquad, triplequad}\n\
 @end deftypefn")
 {
-  octave_value_list retval;
+  int nargin = args.length ();
 
-  std::string fcn_name;
+  if (nargin < 3 || nargin > 5)
+    print_usage ();
 
   warned_imaginary = false;
 
@@ -194,10 +195,7 @@
   if (call_depth > 1)
     error ("quad: invalid recursive call");
 
-  int nargin = args.length ();
-
-  if (nargin < 3 || nargin > 5)
-    print_usage ();
+  std::string fcn_name;
 
   if (args(0).is_function_handle () || args(0).is_inline_function ())
     quad_fcn = args(0).function_value ();
@@ -215,6 +213,8 @@
   if (! quad_fcn)
     error ("quad: FCN argument is not a valid function name or handle");
 
+  octave_value_list retval;
+
   if (args(1).is_single_type () || args(2).is_single_type ())
     {
       float a = args(1).xfloat_value ("quad: lower limit of integration A must be a scalar");