maint: Deprecate is_sorted and replace with issorted. * ov.h (is_sorted): Use OCTAVE_DEPRECATED macro around function. * ov.h (issorted): New function. * Array.h (is_sorted): Use OCTAVE_DEPRECATED macro around function. * Array.h (issorted): New function. * Range.h (is_sorted): Use OCTAVE_DEPRECATED macro around function. * Range.h (issorted): New function. * oct-sort.h (is_sorted): Use OCTAVE_DEPRECATED macro around function. * oct-sort.h (issorted): New function. * data.cc, __ode15__.cc, ov-base-diag.h, ov-base-mat.h, ov-base-scalar.h, ov-base-sparse.h, ov-base.cc, ov-base.h, ov-cell.cc, ov-cell.h, ov-lazy-idx.cc, ov-lazy-idx.h, ov-perm.h, ov-range.h, ov-re-mat.cc, ov-re-mat.h, Array-d.cc, Array-f.cc, Array.cc, Range.cc, oct-sort.cc: Replace instances of is_sorted with issorted.

--- a/liboctave/array/Range.cc	Tue Jun 13 11:25:31 2017 -0700
+++ b/liboctave/array/Range.cc	Tue Jun 13 12:43:42 2017 -0700
@@ -287,7 +287,7 @@
 }
 
 sortmode
-Range::is_sorted (sortmode mode) const
+Range::issorted (sortmode mode) const
 {
   if (rng_numel > 1 && rng_inc > 0)
     mode = (mode == DESCENDING) ? UNSORTED : ASCENDING;