maint: Deprecate is_complex_type and replace with iscomplex. * ov.h (is_complex_type): Use OCTAVE_DEPRECATED macro around function. * ov.h (iscomplex): New function. * __ichol__.cc, __ilu__.cc, balance.cc, bsxfun.cc, cellfun.cc, conv2.cc, daspk.cc, dasrt.cc, dassl.cc, data.cc, det.cc, dot.cc, fft.cc, fft2.cc, fftn.cc, filter.cc, find.cc, givens.cc, graphics.cc, gsvd.cc, hess.cc, hex2num.cc, inv.cc, kron.cc, lookup.cc, ls-mat-ascii.cc, ls-mat4.cc, ls-mat5.cc, lsode.cc, lu.cc, matrix_type.cc, mex.cc, mgorth.cc, ordschur.cc, pinv.cc, psi.cc, quad.cc, qz.cc, rcond.cc, schur.cc, sparse-xpow.cc, sparse.cc, sqrtm.cc, svd.cc, sylvester.cc, symtab.cc, typecast.cc, variables.cc, xnorm.cc, __eigs__.cc, amd.cc, ccolamd.cc, chol.cc, colamd.cc, qr.cc, symbfact.cc, ov-base.h, ov-complex.h, ov-cx-diag.h, ov-cx-mat.h, ov-cx-sparse.h, ov-flt-complex.h, ov-flt-cx-diag.h, ov-flt-cx-mat.h, jit-typeinfo.cc, pt-tm-const.cc: Replace instances of is_complex_type with iscomplex.

--- a/libinterp/corefcn/hess.cc	Mon Jun 12 17:53:28 2017 -0700
+++ b/libinterp/corefcn/hess.cc	Mon Jun 12 21:18:23 2017 -0700
@@ -87,7 +87,7 @@
             retval = ovl (result.unitary_hess_matrix (),
                           result.hess_matrix ());
         }
-      else if (arg.is_complex_type ())
+      else if (arg.iscomplex ())
         {
           FloatComplexMatrix ctmp = arg.float_complex_matrix_value ();
 
@@ -114,7 +114,7 @@
             retval = ovl (result.unitary_hess_matrix (),
                           result.hess_matrix ());
         }
-      else if (arg.is_complex_type ())
+      else if (arg.iscomplex ())
         {
           ComplexMatrix ctmp = arg.complex_matrix_value ();