maint: update GPL license text and license header blocks

* COPYING: Update to the latest upstream license text from gnu.org.
* doc/liboctave/gpl.texi: Likewise.
* __alltohandles__.m, __default__input__.m, tfqmr.m: Update GPLv3 license
header punctuation and formatting for consistency.

Author: mtmiller

COPYING

@@ -1,7 +1,7 @@
                     GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007
 
- Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
@@ -671,4 +671,4 @@ into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

doc/liboctave/gpl.texi

@@ -23,7 +23,7 @@
 @center Version 3, 29 June 2007
 
 @display
-Copyright @copyright{} 2007 Free Software Foundation, Inc. @url{http://fsf.org/}
+Copyright @copyright{} 2007 Free Software Foundation, Inc. @url{https://fsf.org/}
 
 Everyone is permitted to copy and distribute verbatim copies of this
 license document, but changing it is not allowed.
@@ -641,12 +641,12 @@ later version.
 @item Disclaimer of Warranty.
 
 THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
-APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+APPLICABLE LAW@.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
 HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM ``AS IS'' WITHOUT
 WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND
-PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE PROGRAM PROVE
+A PARTICULAR PURPOSE@.  THE ENTIRE RISK AS TO THE QUALITY AND
+PERFORMANCE OF THE PROGRAM IS WITH YOU@.  SHOULD THE PROGRAM PROVE
 DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
 CORRECTION.
 
@@ -698,11 +698,11 @@ your option) any later version.
 
 This program 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
+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 this program.  If not, see @url{http://www.gnu.org/licenses/}.
+along with this program.  If not, see @url{https://www.gnu.org/licenses/}.
 @end smallexample
 
 Also add information on how to contact you by electronic and paper mail.
@@ -725,11 +725,11 @@ use an ``about box''.
 You should also get your employer (if you work as a programmer) or school,
 if any, to sign a ``copyright disclaimer'' for the program, if necessary.
 For more information on this, and how to apply and follow the GNU GPL, see
-@url{http://www.gnu.org/licenses/}.
+@url{https://www.gnu.org/licenses/}.
 
 The GNU General Public License does not permit incorporating your
 program into proprietary programs.  If your program is a subroutine
 library, you may consider it more useful to permit linking proprietary
 applications with the library.  If this is what you want to do, use
 the GNU Lesser General Public License instead of this License.  But
-first, please read @url{http://www.gnu.org/philosophy/why-not-lgpl.html}.
+first, please read @url{https://www.gnu.org/licenses/why-not-lgpl.html}.

scripts/sparse/private/__alltohandles__.m

@@ -2,9 +2,9 @@
 ##
 ## This file is part of Octave.
 ##
-## Octave is free software; you can redistribute it and/or modify it
+## 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
+## 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
@@ -13,8 +13,8 @@
 ## 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/>.
+## along with Octave; see the file COPYING.  If not, see
+## <https://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
 ## @deftypefn  {} {[@var{Afun}, @var{M1fun}, @var{M2fun}] =} __alltohandles__ (@var{A}, @var{b}, @var{M1}, @var{M2}, @var{solver_name})

scripts/sparse/private/__default__input__.m

@@ -2,9 +2,9 @@
 ##
 ## This file is part of Octave.
 ##
-## Octave is free software; you can redistribute it and/or modify it
+## 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
+## 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
@@ -13,8 +13,8 @@
 ## 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/>.
+## along with Octave; see the file COPYING.  If not, see
+## <https://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
 ## @deftypefn  {} {@var{[varargout]} =} __default__input__ (@var{def_val}, @var{varargin})

scripts/sparse/tfqmr.m

@@ -2,10 +2,10 @@
 ##
 ## This file is part of Octave.
 ##
-## Octave is free software; you can redistribute it and/or modify it
+## 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.
+## 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
@@ -14,7 +14,7 @@
 ##
 ## 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/>.
+## <https://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
 ## @deftypefn  {} {@var{x} =} tfqmr (@var{A}, @var{b}, @var{tol}, @var{maxit}, @var{M1}, @var{M2}, @var{x0}, @dots{})