more mouse interaction features for Qt plotting widget * graphics.in.h, graphics.cc (figure::properties::__mouse_mode__, figure::properties::__pan_mode__, figure::properties::__rotate_mode__, figure::properties::__zoom_mode__): New properties. (figure::properties::set___mouse_mode__): New function. (axes::properties::pan, axes::properties::rotate3d, axes::properties::zoom): New functions. Handle zoom, and pan modes. (axes::properties::clear_zoom_stack): New arg, do_unzoom. Conditionally call unzoom. (axes::properties::unzoom): Also restore view property. (axes::properties::rotate_view): Conditionall save state to zoom stack. (axes::properties::push_zoom_stack): New function. (axes::properties::pan, axes::properties::rotate3d): Delete properties. (axes::properties::update_xlim, axes::properties::update_ylim, axes::properties::update_zlim): Don't clear zoom stack. Delete do_clr_zoom argument. (axes::properties::set_pan, axes::properties::set_rotate3d): Delete. (F__zoom__): New function. * Canvas.h, Canvas.cc (Canvas::toggleAxes, Canvas::toggleGrid): New pure virtual functions. (Canvas::setCursor, Canvas::canvasToggleAxes, Canvas::canvasToggleGrid, Canvas::canvasMouseDoubleClickEvent, Canvas::canvasWheelEvent): New functions. (zoom_enabled, pan_enabled, pan_mode, rotate_enabled, rotate_mode): New static functions. (Canvas::canvasMouseMoveEvent): Call axes::properties::rotate3d to do rotation. Handle panning. (Canvas::canvasMousePressEvent): Also handle "unzoom" action when in pan and rotate modes. (Canvas::canvasMouseReleaseEvent): Zoom by factor if mouse has not moved from mouse press event. * Figure.h, Figure.cc (MouseMode): New enum value, TextMode. (Figure::m_mouseMode, Figure::m_lastMouseMode): Delete member variables. (Figure::mouseMode, Figure::setMouseMode): Get info from and save info to figure properties. (Figure::updateFigureToolBarAndMenuBar, Figure::toggleAxes, Figure::toggleGrid): New functions. (Figure::m_mouseModeGroup): New member variable. (Figure::createFigureToolBarAndMenuBar): Add actions for toggling Axes and Grid. Maintain pointer to MouseModeActionGroup. (mouse_mode_to_string, mouse_mode_from_string): New functions. * GLCanvas.h, GLCanvas.cc (GLCanvas::toggleAxes, GLCanvas::ToggleGrid, GLCanvas::mouseDoubleClickEvent, GLCanvas::wheelEvent): New functions. * MouseModeActionGroup.h, MouseModeActionGroup.cc (MouseModeActionGroup::mouseMode): Delete. (MouseModeActionGroup::setMode): New function. (MouseModeActionGroup::MouseModeActionGroup): Also include action to insert text in the list. * figure.m: Set default pan, rotate, and zoom mode properties for the figure object. * pan.m, rotate3d.m, zoom.m: Improve compatibility with Matlab. Set mode properties for figure. * __init_fltk__.cc: Cope with changes to graphics properties.

## Copyright (C) 2006-2013 Daniel Sebald
##
## 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/>.

## -*- texinfo -*-
## @deftypefn {Function File} {@var{version} =} __gnuplot_version__ ()
## Undocumented internal function.
## @end deftypefn

## Return the version of gnuplot we are using.  Note that we do not
## attempt to handle the case of the user switching to different
## versions of gnuplot during the same session.

function version = __gnuplot_version__ ()

  persistent __version__ = "";

  if (isempty (__version__))
    [status, output] = system (sprintf ('"%s" --version', gnuplot_binary ()));
    if (status != 0)
      ## This message ends in a newline so that the traceback messages
      ## are skipped and people might actually see the message, read it,
      ## comprehend it, take the advice it gives, and stop asking us
      ## why plotting fails when gnuplot is not found.
      error ("you must have gnuplot installed to display graphics; if you have gnuplot installed in a non-standard location, see the 'gnuplot_binary' function\n");
    endif
    output = strrep (output, "gnuplot", "");
    output = strrep (output, "patchlevel", ".");
    output = strrep (output, "\n", "");
    output = strrep (output, "\r", "");
    __version__ = strrep (output, " ", "");
  endif

  version = __version__;

endfunction