Update a few copyright years to 2021

COPYING

@@ -6,7 +6,7 @@ This file is Copyrighted
 
     This file is covered under the following Copyright:
 
-	Copyright (C) 1999-2014  Landon Curt Noll
+	Copyright (C) 1999-2021  Landon Curt Noll
 	All rights reserved.
 
 	Everyone is permitted to copy and distribute verbatim copies

Makefile

@@ -12,6 +12,8 @@
 #	 USE_READLINE= -DUSE_READLINE
 #	 READLINE_LIB= -lreadline -lhistory -lncurses
 #
+# Copyright (C) 1999-2018,2021  Landon Curt Noll
+#
 # The Makefile.ship makefile becomes the Makefile found in the
 # calc-*.tar.bz2 bzip2 source tarball.
 #

calc.h

@@ -1,7 +1,7 @@
 /*
  * calc - definitions for calculator program
  *
- * Copyright (C) 1999-2007,2014  David I. Bell
+ * Copyright (C) 1999-2007,2014,2021  David I. Bell
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License

help.c

@@ -1,7 +1,7 @@
 /*
  * help - display help for calc
  *
- * Copyright (C) 1999-2007,2014,2018  Landon Curt Noll
+ * Copyright (C) 1999-2007,2014,2018,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License

lib_calc.c

@@ -1,7 +1,7 @@
 /*
  * lib_calc - calc link library initialization and shutdown routines
  *
- * Copyright (C) 1999-2007,2018  Landon Curt Noll
+ * Copyright (C) 1999-2007,2018,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License

lib_calc.h

@@ -1,7 +1,7 @@
 /*
  * math_error - a simple libcalc math error routine
  *
- * Copyright (C) 1999-2007,2014  Landon Curt Noll
+ * Copyright (C) 1999-2007,2014,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License