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.

To cite GNU Octave in publications use:

  John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring (2014).
  GNU Octave version 3.8.1 manual: a high-level interactive language for
  numerical computations.
  CreateSpace Independent Publishing Platform.  ISBN 1441413006,
  URL http://www.gnu.org/software/octave/doc/interpreter/

A BibTeX entry for LaTeX users is:

  @book{,
    author    = {John W. Eaton, David Bateman, S\oren Hauberg, and Rik Wehbring},
    title     = {{GNU Octave} version 3.8.1 manual: a high-level interactive language for numerical computations},
    publisher = {CreateSpace Independent Publishing Platform},
    year      = {2014},
    note      = {{ISBN} 1441413006},
    url       = {http://www.gnu.org/software/octave/doc/interpreter},
  }

We have invested a lot of time and effort in creating GNU Octave, please cite it
when using it.  See also `citation pkgname' for citing Octave packages.