make units other than data work for axes labels and title (bug #35857) * graphics.in.h, graphics.cc (base_property::invalidate): New function. (axes::properties::set_defaults): If mode is not "reset", invalidate label and title handles before recreating them. Don't notify toolkit when recreating label and title handles. Update label and title positions after they are created. (convert_label_position): New static function. (axes::properties::update_xlabel_position, axes::properties::update_ylabel_position, axes::properties::update_zlabel_position, axes::properties::update_title_position): Return early if object is not valid. Call convert_label_position to handle units other than "data". (text::properties::update_units): Preserve "auto" positionmode. (gh_manager::do_make_graphics_handle): Call override_defaults here for newly created objects. If creating an axes object, also call override_defaults for the axes label and title objects. (graphics_object::override_defaults): New function. (figure::figure, axes::axes, line::line, text::text, image::image, patch::patch, surface::surface, hggroup::hggroup, uimenu::uimenu, uicontextmenu::uicontextmenu, uicontrol::uicontrol, uipanel::uipanel, uitoolbar::uitoolbar, uipushtool::uipushtool, uitoggletool::uitoggletool): Don't call override_defaults from constructor.

## Copyright (C) 2006-2015 John W. Eaton
##
## This file is part of Octave.
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or (at
## your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

%!function y = f ()
%!  y = 1;
%!  return;
%!  y = 2;
%!endfunction
%!
%!assert (f (), 1)

%!test
%! return;