[racket] ANN: 2048 game - Racket edition

Very nice, Dan!  Just played a good round of it.  Three comments:

* The window disappeared and program exited as soon as I couldn't move 
anymore.  (No score, no chance to screenshot, etc.)

* The color palette is pretty important, for two reasons: (1) 
aesthetically pleasing; and (2) visual indication of high and low 
pieces, as well as of matching pieces.  (128 looks very similar to 2, 
for example, and there was no color help to indicate the positions of 
the 512, 256, and 128, when I was trying to bring them together.)

* As the game progressed, the animation generally seemed a little 
choppier, as if it had fewer frames than earlier in the game.  I don't 
know whether it was GC cycles, some graphics layer overhead that is hard 
to account for or control, or some app function that could use tweaking.

BTW, you might want to touch bases with some of the authors of the other 
games in this family.  I talked with the 2048 author recently (about 
adding 2048 to the OpenWrt management console), and s/he was gracious 
and enthusiastic.

Also BTW, have no *students* yet implemented this game in Racket? Stop 
slacking, and get with the program, students!

Neil V.