add repr for genome and gene;

add ipynb test for testing whether add node or add conn will not change the output for the network.

tensorneat/algorithm/neat/gene/conn/default.py

@@ -60,3 +60,19 @@ class DefaultConnGene(BaseConnGene):
     def forward(self, state, attrs, inputs):
         weight = attrs[0]
         return inputs * weight
+
+    def repr(self, state, conn, precision=2, idx_width=3, func_width=8):
+        in_idx, out_idx, weight = conn
+
+        in_idx = int(in_idx)
+        out_idx = int(out_idx)
+        weight = round(float(weight), precision)
+
+        return "{}(in: {:<{idx_width}}, out: {:<{idx_width}}, weight: {:<{float_width}})".format(
+            self.__class__.__name__,
+            in_idx,
+            out_idx,
+            weight,
+            idx_width=idx_width,
+            float_width=precision + 3,
+        )