Added simple effect system

ledd/effects/generatoreffect.py

@@ -0,0 +1,30 @@
+
+from ledd.effects.baseeffect import BaseEffect
+from spectra import Color
+
+
+class GeneratorEffect(BaseEffect):
+    """
+    This is a base class for simple effects.
+    It should yield a new color on each execution.
+    """
+
+    def __init__(self):
+        """
+        Do not override, use setup instead.
+        """
+        self.generator = self.execute()
+
+    def setup(self):
+        pass
+
+    def execute_internal(self):
+        c = next(self.generator)
+        assert isinstance(c, Color)
+        return c
+
+    def execute(self):
+        pass
+
+    def tear_down(self):
+        pass