New magic tool: Pixels

Suitable for simple 'pixel art'.  Draws 8x8 pixel rectangles on
a grid across the canvas.

Sound effect created via a small Atari BASIC program sampled in
the open source 'Atari800' emulator (emulating the POKEY sound
chip), and trimmed in Audacity.

docs/en/html/README.html

@@ -28,14 +28,14 @@
       </h3>
 
       <p>
-        Copyright 2002-2020 by various contributors; see
+        Copyright 2002-2021 by various contributors; see
         AUTHORS.txt<br>
         <a href=
         "http://www.tuxpaint.org/">http://www.tuxpaint.org/</a>
       </p>
 
       <p>
-        June 14, 2002 - December 27, 2020
+        June 14, 2002 - January 6, 2021
       </p>
     </center>