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/time.cc	Fri Dec 18 16:22:53 2015 -0500
+++ b/libinterp/corefcn/time.cc	Fri Dec 18 15:37:22 2015 -0800
@@ -117,7 +117,7 @@
   if (args.length () != 0)
     print_usage ();
 
-  return octave_value (octave_time ());
+  return ovl (octave_time ());
 }
 
 /*
@@ -161,7 +161,7 @@
 
   double tmp = args(0).double_value ();
 
-  return octave_value (mk_tm_map (octave_gmtime (tmp)));
+  return ovl (mk_tm_map (octave_gmtime (tmp)));
 }
 
 /*
@@ -216,7 +216,7 @@
 
   double tmp = args(0).double_value ();
 
-  return octave_value (mk_tm_map (octave_localtime (tmp)));
+  return ovl (mk_tm_map (octave_localtime (tmp)));
 }
 
 /*
@@ -262,7 +262,7 @@
 
   octave_base_tm tm = extract_tm (map, "mktime");
 
-  return octave_value (octave_time (tm));
+  return ovl (octave_time (tm));
 }
 
 /*
@@ -451,7 +451,7 @@
 
   octave_base_tm tm = extract_tm (map, "strftime");
 
-  return octave_value (tm.strftime (fmt));
+  return ovl (tm.strftime (fmt));
 }
 
 /*