Added rotary encoder example

examples/rotary-encoder-stemma.py

@@ -0,0 +1,33 @@
+# Ref: https://learn.adafruit.com/adafruit-i2c-qt-rotary-encoder/python-circuitpython
+import board
+from adafruit_seesaw import seesaw, rotaryio, digitalio
+import busio
+
+SDA = board.GP0
+SCL = board.GP1
+i2c = busio.I2C(SCL, SDA)
+seesaw = seesaw.Seesaw(i2c, 0x36)
+
+seesaw.pin_mode(24, seesaw.INPUT_PULLUP)
+button = digitalio.DigitalIO(seesaw, 24)
+button_held = False
+
+encoder = rotaryio.IncrementalEncoder(seesaw)
+last_position = None
+
+while True:
+
+    # negate the position to make clockwise rotation positive
+    position = -encoder.position
+
+    if position != last_position:
+        last_position = position
+        print("Position: {}".format(position))
+
+    if not button.value and not button_held:
+        button_held = True
+        print("Button pressed")
+
+    if button.value and button_held:
+        button_held = False
+        print("Button released")