Implement moving on engine

Thus make all state management the engine's responsibility, and remove
the state maintaining code from frontend!

adapter/adapter.py

@@ -60,5 +60,12 @@ def get_moves():
     return flask.jsonify(moves)
 
 
+@app.route("/make_move/", methods=["POST"])
+def make_move():
+    source, target = flask.request.json
+    state_str = ask_engine(f"make_move,{source},{target}")
+    return flask.jsonify(parse_state(state_str))
+
+
 if __name__ == "__main__":
     app.run(debug=True, host="127.0.0.1", port=3000)