Added ColorEightByEight class and example program for Adafruit Bicolor LED Square Pixel Matrix with I2C Backpack

Added note about possible pixel indexing bug in the non-color version.  I don't have the non-color version to test with.

Added note about possible unintentional color "blending" bug in the Arduino color version.

Author: mprice

Adafruit_LEDBackpack/ex_8x8_color_pixels.py

@@ -0,0 +1,31 @@
+#!/usr/bin/python
+
+import time
+import datetime
+from Adafruit_8x8 import ColorEightByEight
+
+# ===========================================================================
+# 8x8 Pixel Example
+# ===========================================================================
+grid = ColorEightByEight(address=0x70)
+
+print "Press CTRL+Z to exit"
+
+iter = 0
+
+# Continually update the 8x8 display one pixel at a time
+while(True):
+  iter += 1
+
+  print (iter % 4)
+
+  for x in range(0, 8):
+    for y in range(0, 8):
+      grid.setPixel(x, y, iter%4 )
+      time.sleep(0.02)
+
+# I think there is another bug here that drawing red or green after yellow doesn't clear the other component until you draw a blank
+
+#  time.sleep(0.5)
+#  grid.clear()
+#  time.sleep(0.5)