replaced usleep for windows

New: changed 2000 into a constant defined inline

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- 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 ...

Ok, I will merge this as you've changed it. But note the biggest impact to this change is that it introduces latency to the audio pipeline, which is one of our "fetishes"... we want as low a latency as possible. You should be able to read this before I'm done typing it.