Add a really simple burn-in test helper

examples/python/burnin.py

+#!/usr/bin/env python
+
+# Burn-in test: Keep LEDs at full brightness most of the time, but dim periodically
+# so it's clear when there's a problem.
+
+import opc, time, math
+
+numLEDs = 512
+client = opc.Client('localhost:7890')
+
+t = 0
+
+while True:
+    t += 0.4
+    brightness = int(min(1, 1.25 + math.sin(t)) * 255)
+    frame = [ (brightness, brightness, brightness) ] * numLEDs
+    client.put_pixels(frame)
+    time.sleep(0.05)