replaced usleep for windows

- Added functions to test usleep, msleep and sleep for accuracy. 
- Replaced windows usleep version with a non busy waiting high accuracy Version.
- Modified CALLBACK_ACCELERATOR_RATIO for windows because some systems need larger input buffer to work fine.

There are still issues when the framerate drops but that will be another worklist item ...

Not without some metric to determine the actual limiting factors at startup. For now I suggest changing the value to the new value. It affects only the underlying QAudioInput input buffer size on windows by factor 4 enlarging it from 2560 bytes to 10240 bytes. This way Qt won't run that fast into problems on systems with heavy load. No other penalties.

I think that the dynamical determination can get adressed when we further analyze the audio issues that come in when having framerate drops and/or heavy network traffic. We'll have to find a way how audio quality gets adjusted according to bandwith availability, system capabilities and overall load. If you have a heavy loaded limited machine in a slow high latency network the system has to automatically adjust to low quality using less bandwidth. When using a powerful machine with low load in a high performance low latency networking environment the system has to use best audio quality. The algorithm for all that will cover your initial requirement too. But this algorithm has to get developed first.