move rainbow generation to lights

so we can support lights with multiple pixels properly

lights/common.py

@@ -1,4 +1,5 @@
 import logging
+from colorsys import hsv_to_rgb
 
 LOG = logging.getLogger('DMX')
 
@@ -22,3 +23,21 @@ class BaseDMXLight:
         ret = self._dump()
         LOG.debug(f'{str(self)} -> {ret[1]}')
         return ret
+
+    def rainbow(self, idx, angle, number_of_lights, intensity, brightness):
+        my_degrees_dec = (
+            (angle + (idx * (360 / number_of_lights))) % 360 / 360
+        )
+        r, g, b = hsv_to_rgb(
+            my_degrees_dec,
+            1,
+            intensity / 100,
+        )
+
+        self.red = int(r * 255)
+        self.green = int(g * 255)
+        self.blue = int(b * 255)
+        self.white = 0
+        self.intensity = brightness
+
+        return self.dump()