Added residual layer example. Fixed some bugs in the process.

tests/test_ff_residual.py

@@ -0,0 +1,38 @@
+from manim import *
+from manim_ml.neural_network import NeuralNetwork, FeedForwardLayer, MathOperationLayer
+
+# Make the specific scene
+config.pixel_height = 1200
+config.pixel_width = 1900
+config.frame_height = 6.0
+config.frame_width = 6.0
+
+class TestFeedForwardResidualNetwork(Scene):
+
+    def construct(self):
+        # Add the network
+        nn = NeuralNetwork({
+                "feed_forward_1": FeedForwardLayer(3),
+                "feed_forward_2": FeedForwardLayer(3, activation_function="ReLU"),
+                "feed_forward_3": FeedForwardLayer(3),
+                "sum_operation": MathOperationLayer("+", activation_function="ReLU"),
+            },
+            layer_spacing=0.38
+        )
+        self.add(nn)
+        # Make connections
+        input_blank_dot = Dot(
+            nn.input_layers_dict["feed_forward_1"].get_left() - np.array([0.65, 0.0, 0.0])
+        )
+        nn.add_connection(input_blank_dot, "feed_forward_1", arc_direction="straight")
+        nn.add_connection("feed_forward_1", "sum_operation")
+        output_blank_dot = Dot(
+            nn.input_layers_dict["sum_operation"].get_right() + np.array([0.65, 0.0, 0.0])
+        )
+        nn.add_connection("sum_operation", output_blank_dot, arc_direction="straight")
+
+        # Make forward pass animation
+        self.play(
+            nn.make_forward_pass_animation()
+        )
+