add feedforward substrate and hyperneat and related example;

see https://github.com/EMI-Group/tensorneat/issues/9;
fix bugs in genome visualize (add plt.close())

test/mlp_substrate.py

@@ -0,0 +1,6 @@
+from tensorneat.algorithm.hyperneat.substrate.mlp import MLPSubstrate, analysis_substrate
+
+layers = [3, 4, 2]
+coor_range = (-1, 1, -1, 1)
+nodes = analysis_substrate(layers, coor_range)
+print(nodes)