Restore support for assigning a list to strip[:]

This functionality was lost in commit:
  f80276b

Signed-off-by: David Greaves <david@dgreaves.com>

Author: lbt

library/rpi_ws281x/rpi_ws281x.py

@@ -106,14 +106,19 @@ def __getitem__(self, pos):
 
     def __setitem__(self, pos, value):
         """Set the 24-bit RGB color value at the provided position or slice of
-        positions.
+        positions. If value is a slice it is zip()'ed with pos to set as many
+        leds as there are values.
         """
         # Handle if a slice of positions are passed in by setting the appropriate
         # LED data values to the provided value.
         # Cast to int() as value may be a numpy non-int value.
         if isinstance(pos, slice):
-            for n in range(*pos.indices(self.size)):
-                ws.ws2811_led_set(self._channel, n, int(value))
+            try:
+                for n, c in zip(range(*pos.indices(self.size)), value):
+                    ws.ws2811_led_set(self._channel, n, int(c))
+            except TypeError:
+                for n in range(*pos.indices(self.size)):
+                    ws.ws2811_led_set(self._channel, n, int(value))
         # Else assume the passed in value is a number to the position.
         else:
             return ws.ws2811_led_set(self._channel, pos, int(value))