Adds a function set_led() to the library to control the built-in LED for the r503 sensor.
def set_led(self, color=1, mode=3, speed=0x80, cycles=0):
"""LED function -- only for R503 Sensor.
Parameters: See User Manual for full details
color: 1=red, 2=blue, 3=purple
mode: 1-breathe, 2-flash, 3-on, 4-off, 5-fade_on, 6-fade-off
speed: animation speed 0-255
cycles: numbe of time to repeat 0=infinite or 1-255
Returns the packet error code or success"""
Added examples for r503 that demonstrate some led functions.
Details regarding the LED control are in the Users Manual
https://cdn-shop.adafruit.com/product-files/4651/4651_R503+fingerprint+module+user+manual.pdf