doc: Rewrite documentation for Object Oriented Programming. * octave.texi: Rename "Manipulating Classes" node to "Class Methods" * oop.txi: Rewrite signicant parts of Object Oriented Programming chapter. * examples/code/@FIRfilter/subsasgn.m, examples/code/@FIRfilter/subsref.m, examples/code/@polynomial/get.m, examples/code/@polynomial/subsasgn.m: Enclose property in error messages in double quotes ("%s"). * examples/code/@polynomial/subsref.m: Rename input object to 'p'. Rename variable "ind" to "idx". Enclose property in error messages in double quotes ("%s"). * ov-class.cc (Fsuperiorto, Finferiorto): Improve docstrings. * ov-usr-fcn.cc (Foptimize_subsasgn_calls): Improve docstring. * ov.cc (Fsubsref, Fsubsasgn): Improve docstrings. * display.m: Rewrite docstring. Rename input variable to "obj". Remove unused output variable from function declaration. * subsindex.m: Rename input variable to "obj". Rewrite examples in docstring. Add input validation and BIST tests to m-file.

function r = subsref (f, x)

  switch (x.type)

    case "()"
      n = f.polynomial;
      r = filter (n.poly, 1, x.subs{1});

    case "."
      fld = x.subs;
      if (! strcmp (fld, "polynomial"))
        error ('@FIRfilter/subsref: invalid property "%s"', fld);
      endif
      r = f.polynomial;

    otherwise
      error ("@FIRfilter/subsref: invalid subscript type for FIR filter");

  endswitch

endfunction