changes to SparseParams class

[John W. Eaton]

I just checked in the following change:

liboctave/ChangeLog:

        * oct-spparms.h, oct-spparms.cc (class octave_sparse_params):
        Rename from SparseParams.  Use same implementation method as other
        singleton classes in Octave.  Change all uses of
        Voctave_sparse_controls to use static functions from
        octave_sparse_params class instead.

It's probably not useful to send diffs.  The new class should do the
same as what was intended by the previous code, but using the style of
singleton objects that is used in the rest of Octave.  The old way of
initializing Voctave_sparse_controls from inside the SparseParams
constructor seemed a bit strange to me.  Now instead of writing (for
example)

  Voctave_sparse_controls.print_info (octave_stdout, "");

you need to write

  octave_sparse_params::print_info (octave_stdout, "");

jwe