Update TicTacToe3D.pde

Updated the code to work on Processing 2.0.3 as 1.5.1 does not run on operating systems without 32bit Java support (OSX 10.8/10.9 for example).

Visual output is slightly modified due to a current regression in Processing with its new OpenGL renderer as can be seen here:

https://github.com/processing/processing/issues/2051