use gyro rate to extrapolate gyro to account for measurement lag

[truher]

the navx sensor loop runs at about 400hz, 2.5ms max, 1.25 ms mean

the SPI input runs in a 200hz thread, 5ms max, 2.5 ms mean

the payload itself is 80 bytes (!) so that takes about 1.25 ms at 0.5 mhz

so the total delay is about 5ms.