maint: Deprecate is_sparse_type and replace with issparse. * ov.h (is_sparse_type): Use OCTAVE_DEPRECATED macro around function. * ov.h (issparse): New function. * __luinc__.cc, bsxfun.cc, cellfun.cc, data.cc, det.cc, find.cc, gcd.cc, graphics.in.h, inv.cc, kron.cc, ls-mat4.cc, ls-mat5.cc, lu.cc, matrix_type.cc, max.cc, mex.cc, rcond.cc, sparse.cc, tril.cc, variables.cc, xnorm.cc, __eigs__.cc, __glpk__.cc, amd.cc, ccolamd.cc, chol.cc, colamd.cc, qr.cc, ov-base-sparse.h, ov-base.h, ov-bool-mat.cc, pt-tm-const.cc: Replace instances of is_sparse_type with issparse.

--- a/libinterp/corefcn/bsxfun.cc	Tue Jun 13 07:53:53 2017 -0700
+++ b/libinterp/corefcn/bsxfun.cc	Tue Jun 13 08:24:42 2017 -0700
@@ -466,7 +466,7 @@
 
               if (i == 0)
                 {
-                  if (! tmp(0).is_sparse_type ())
+                  if (! tmp(0).issparse ())
                     {
                       std::string result_type = tmp(0).class_name ();
                       if (result_type == "double")