Add compiling packnet model, refactor modules to not duplicate loaders and trainers

metric.py

@@ -0,0 +1,16 @@
+import tensorflow as tf
+
+
+def delta1_metric(y_true, y_pred):
+    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
+    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25), tf.float32))
+
+
+def delta2(y_true, y_pred):
+    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
+    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25 ** 2), tf.float32))
+
+
+def delta3(y_true, y_pred):
+    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
+    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25 ** 3), tf.float32))