Visualizer refresh rate doesn't depend on `refreshRate`

[ethanbb]

Currently, the refreshRate field in Visualizer.h, which claims to set the refresh rate in Hz, isn't used anywhere (as far as I can tell). The startCallbacks function in Visualizer.cpp:

void Visualizer::startCallbacks()
{
	startTimer(20);
}

always starts the timer with a refresh period of 20 ms = 50 Hz (which doesn't match the default refreshRate of 10). To avoid confusion, either refreshRate should be removed or it should be made functional.

[ethanbb]

Thank you!