maint: Eliminate single "Author:" lines from code base. * color-picker.cc, color-picker.h, octave-qscintilla.cc, octave-qscintilla.h, octave-txt-lexer.cc, octave-txt-lexer.h, balance.cc, kron.cc, lookup.cc, ls-hdf5.cc, ls-mat5.cc, ls-oct-text.cc, sylvester.cc, tsearch.cc, jit-ir.cc, jit-ir.h, jit-typeinfo.cc, jit-typeinfo.h, jit-util.cc, jit-util.h, pt-jit.cc, pt-jit.h, Array-jit.cc, bsxfun.h, url-transfer.cc, url-transfer.h, acosd.m, acotd.m, acscd.m, asecd.m, asind.m, atand.m, cosd.m, cotd.m, cscd.m, secd.m, sind.m, tand.m, cart2pol.m, cart2sph.m, curl.m, del2.m, divergence.m, flip.m, pol2cart.m, randi.m, sortrows.m, sph2cart.m, griddata3.m, griddatan.m, rectint.m, voronoi.m, dialog.m, guidata.m, guihandles.m, __file_filter__.m, __fltk_file_filter__.m, __get_funcname__.m, __is_function__.m, __uigetdir_fltk__.m, __uigetfile_fltk__.m, __uiobject_split_args__.m, __uiputfile_fltk__.m, uibuttongroup.m, uicontextmenu.m, uicontrol.m, uigetdir.m, uigetfile.m, uimenu.m, uipanel.m, uipushtool.m, uiputfile.m, uiresume.m, uitoggletool.m, uitoolbar.m, uiwait.m, doc.m, autumn.m, bone.m, cmpermute.m, cmunique.m, cool.m, copper.m, cubehelix.m, flag.m, frame2im.m, hot.m, hsv.m, hsv2rgb.m, im2frame.m, imfinfo.m, imformats.m, iscolormap.m, jet.m, pink.m, prism.m, __imfinfo__.m, rainbow.m, rgb2hsv.m, spinmap.m, spring.m, viridis.m, white.m, winter.m, importdata.m, strmatch.m, bandwidth.m, isbanded.m, isdiag.m, istril.m, istriu.m, krylov.m, linsolve.m, logm.m, lscov.m, subspace.m, bunzip2.m, compare_versions.m, edit.m, fullfile.m, getfield.m, gunzip.m, inputParser.m, license.m, nargchk.m, narginchk.m, nthargout.m, python.m, setfield.m, tar.m, unpack.m, ver.m, zip.m, odeplot.m, fminbnd.m, fminunc.m, fsolve.m, fzero.m, glpk.m, humps.m, pathdef.m, savepath.m, diffuse.m, lighting.m, material.m, shading.m, specular.m, contour.m, ellipsoid.m, isocaps.m, isocolors.m, isonormals.m, isosurface.m, light.m, pcolor.m, __interp_cube__.m, __marching_cube__.m, __patch__.m, __stem__.m, reducepatch.m, reducevolume.m, ribbon.m, shrinkfaces.m, slice.m, stem.m, surf.m, surfl.m, tetramesh.m, waterfall.m, __actual_axis_position__.m, __next_line_color__.m, allchild.m, figure.m, findall.m, findobj.m, gcf.m, hggroup.m, isprop.m, ndgrid.m, __add_default_menu__.m, saveas.m, __splinefit__.m, prefdir.m, preferences.m, profexplore.m, profexport.m, profile.m, profshow.m, setdiff.m, freqz.m, freqz_plot.m, sinc.m, unwrap.m, pcr.m, qmr.m, sprandn.m, betaincinv.m, cosint.m, ellipke.m, factor.m, gammaincinv.m, legendre.m, nchoosek.m, primes.m, invhilb.m, toeplitz.m, erase.m, mat2str.m, strtrim.m, validatestring.m, fail.m, compare_plot_demos.m, dump_demos.m, html_compare_plot_demos.m, addtodate.m, datenum.m, jit.tst: Eliminate single "Author:" lines from code base.

########################################################################
##
## Copyright (C) 2005-2020 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## 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
## <https://www.gnu.org/licenses/>.
##
########################################################################

## -*- texinfo -*-
## @deftypefn {} {@var{h} =} gcf ()
## Return a handle to the current figure.
##
## The current figure is the default target for graphics output.  If multiple
## figures exist, @code{gcf} returns the last created figure or the last figure
## that was clicked on with the mouse.
##
## If a current figure does not exist, create one and return its handle.  The
## handle may then be used to examine or set properties of the figure.  For
## example,
##
## @example
## @group
## fplot (@@sin, [-10, 10]);
## fig = gcf ();
## set (fig, "numbertitle", "off", "name", "sin plot")
## @end group
## @end example
##
## @noindent
## plots a sine wave, finds the handle of the current figure, and then
## renames the figure window to describe the contents.
##
## Note: To find the current figure without creating a new one if it does not
## exist, query the @qcode{"CurrentFigure"} property of the root graphics
## object.
##
## @example
## get (groot, "currentfigure");
## @end example
##
## @seealso{gca, gco, gcbf, gcbo, get, set}
## @end deftypefn

function h = gcf ()

  if (nargin == 0)
    h = get (0, "currentfigure");
    if (isempty (h) || h == 0)
      ## We only have a root object, so create a new figure object
      ## and make it the current figure.
      h = figure ();
    endif
  else
    print_usage ();
  endif

endfunction


%!test
%! hf = figure ("visible", "off");
%! unwind_protect
%!   assert (gcf, hf);
%! unwind_protect_cleanup
%!   close (hf);
%! end_unwind_protect