Refactor many definitions out of topics and into folders within mobject

mobject/frame.py

@@ -0,0 +1,44 @@
+from __future__ import absolute_import
+
+from constants import *
+from mobject.geometry import Rectangle
+from utils.config_ops import digest_config
+
+class ScreenRectangle(Rectangle):
+    CONFIG = {
+        "width_to_height_ratio" : 16.0/9.0,
+        "height" : 4,
+    }
+    def generate_points(self):
+        self.width = self.width_to_height_ratio * self.height
+        Rectangle.generate_points(self)
+
+class FullScreenRectangle(ScreenRectangle):
+    CONFIG = {
+        "height" : FRAME_HEIGHT,
+    }
+
+class FullScreenFadeRectangle(FullScreenRectangle):
+    CONFIG = {
+        "stroke_width" : 0,
+        "fill_color" : BLACK,
+        "fill_opacity" : 0.7,
+    }
+
+class PictureInPictureFrame(Rectangle):
+    CONFIG = {
+        "height" : 3,
+        "aspect_ratio" : (16, 9)
+    }
+    def __init__(self, **kwargs):
+        digest_config(self, kwargs)
+        height = self.height
+        if "height" in kwargs:
+            kwargs.pop("height")
+        Rectangle.__init__(
+            self,
+            width = self.aspect_ratio[0],
+            height = self.aspect_ratio[1],
+            **kwargs
+        )
+        self.scale_to_fit_height(height)