Merge pull request #28 from prcutler/root-group-update

Update with display.root_group for CP 9 compatibility

Author: FoamyGuy

examples/stmpe610_button_demo.py

@@ -61,7 +61,7 @@
 
 # Create the displayio group and show it
 splash = displayio.Group()
-display.show(splash)
+display.root_group = splash
 
 # Defiine the button
 button = Button(

examples/stmpe610_touch_calibrator.py

@@ -89,7 +89,7 @@
 # Activate the display graphics unless REPL_ONLY=True.
 if not REPL_ONLY:
     display_group = displayio.Group()
-    display.show(display_group)
+    display.root_group = display_group
 
 # Instantiate touchscreen.
 ts_cs = digitalio.DigitalInOut(board.D6)