Add DSControlWord::Refresh in C++

[virtuald]

Java has this, but C++ does not. Obviously, it's cheaper to create a DSControlWord object in C++ so it isn't really necessary, but it would be good to avoid creating the object in Python.

Alternatively, make the m_controlWord protected so that I can patch on a refresh method myself for python only.

[KangarooKoala]

For context, I think this was closed because RobotBase exposes the same information as DSControlWord: robotpy/mostrobotpy#161 (comment)