[m-rev.] diff: delete an old graphics sample

[Julien Fischer]

Delete an old graphics sample.

extras/graphics/samples/pent/:
     Delete this; the togl library it used has not been supported
     for many years.

extras/graphics/README:
     Delete the (incorrect) entry for the above.

     Add a missing entry.

Julien.

(Note: I've ommitted the deleted files from the diff.)

diff --git a/extras/graphics/README b/extras/graphics/README
index bc3e264..ab8199f 100644
--- a/extras/graphics/README
+++ b/extras/graphics/README
@@ -23,14 +23,13 @@ and we'll see about incorporating enhancements in the main distribution.
                                  library.

  	samples/
-		calc/		A calculator that uses mercury_tcltk
+		calc/		A calculator that uses mercury_tcltk.

+		gears/		The classic OpenGL gears demo.
+
  		maze/		Draws pretty mazes in 3D using OpenGL
  				and GLUT.

-		pent/		Places pentominoes on a board in 3D 
-				using OpenGL and GLUT.
-
  We haven't worked out how to prevent the Tcl/Tk library from giving a
  tcl prompt when it enters the event loop. If you know how, let us know!