Added functions to test usleep, msleep and sleep for accuracy.
Replaced windows usleep version with a non busy waiting high accuracy version. This fixes the high CPU load for the windows servers too!
Modified CALLBACK_ACCELERATOR_RATIO for windows because some systems need larger input buffer to work fine.
changed 2000 into a constant defined inline
Merge pull request #3025 from talentraspel/19753

replaced usleep for windows