Add counter.py example script, to count number of button presses.

Simple counter for the BBC micro:bit MicroPython for pedagogical purposes.

Author: zitterbewegung

examples/counter.py

@@ -0,0 +1,15 @@
+"""
+    counter.py
+    ~~~~~~~~~~
+    Creates a counter that increments on pressing button a.
+    Scrolls the current count on the led display.
+"""
+
+import microbit
+ctr = 0                                         # Initialize counter
+while True:                                     # Loop forever
+    ctr = ctr + microbit.button_a.get_presses() # Count the amount of presses 
+    microbit.button_a.reset_presses()   
+    if ctr > 0:                                 # Only execute if not zero
+        microbit.display.scroll(str(ctr))       # Display the counter
+    microbit.sleep(100)                         # Sleep for 100ms