Generic sendCommand methods

This release adds a support for generic sendCommand methods. From now, there are two ways how to send a command. You can send it

• with a string format

  std::string commandFormat = "setmotor %d %d %d";
  
  // No response is expected.
  controller.sendFormattedCommand(commandFormat, 20, 20, 5);
  
  // A string response is expected.
  std::string response = controller.sendFormattedCommand<std::string>(commandFormat, 20, 20, 5);

• or with any value that can be written to a stream (parameters are separated by space).

  // No response is expected.
  controller.sendCommand("setmotor", 20, 20, 5);
  
  // An integer response is expected.
  int response = controller.sendCommand<int>("setmotor", 20, 20, 5);