maint: Deprecate is_real_type and replace with isreal. * ov.h (is_real_type): Use OCTAVE_DEPRECATED macro around function. * ov.h (isreal): New function. * QtHandlesUtils.cc, __luinc__.cc, bsxfun.cc, cellfun.cc, conv2.cc, data.cc, det.cc, eig.cc, ellipj.cc, fft.cc, fft2.cc, fftn.cc, find.cc, graphics.cc, graphics.in.h, gsvd.cc, hess.cc, inv.cc, lu.cc, mex.cc, oct-stream.cc, pinv.cc, psi.cc, qz.cc, schur.cc, svd.cc, typecast.cc, chol.cc, dmperm.cc, qr.cc, symbfact.cc, symrcm.cc, ov-base-int.h, ov-base.h, ov-bool-mat.h, ov-bool-sparse.h, ov-bool.h, ov-ch-mat.h, ov-float.h, ov-flt-re-diag.h, ov-flt-re-mat.h, ov-java.cc, ov-lazy-idx.h, ov-perm.h, ov-range.h, ov-re-diag.h, ov-re-mat.h, ov-re-sparse.h, ov-scalar.h, pt-tm-const.cc: Replace instances of is_real_type with isreal.

--- a/libinterp/corefcn/det.cc	Mon Jun 12 21:18:23 2017 -0700
+++ b/libinterp/corefcn/det.cc	Tue Jun 13 07:53:53 2017 -0700
@@ -129,7 +129,7 @@
     }
   else if (arg.is_single_type ())
     {
-      if (arg.is_real_type ())
+      if (arg.isreal ())
         {
           octave_idx_type info;
           float rcond = 0.0;
@@ -162,7 +162,7 @@
     }
   else
     {
-      if (arg.is_real_type ())
+      if (arg.isreal ())
         {
           octave_idx_type info;
           double rcond = 0.0;