Accumulators wait for the next sample after reset

Analog accumulators now wait for the amount of time a full sample
(including oversampling and averaging) lasts after
AnalogInput::ResetAccumulator() is called, so they don't return
old values after being reset.

This delay should be microseconds long and will only happen
when an accumulator is reset.

A new test is is the C++ TiltPanCameraTest that tests this behavior
with the Gyro class.

Change-Id: I1b3ffdeec187959f95c5e637a6d428c9a4bc2cf4

wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/AnalogInput.java

@@ -310,6 +310,14 @@ public class AnalogInput extends SensorBase implements PIDSource,
 		status.order(ByteOrder.LITTLE_ENDIAN);
 		AnalogJNI.resetAccumulator(m_port, status.asIntBuffer());
 		HALUtil.checkStatus(status.asIntBuffer());
+
+		// Wait until the next sample, so the next call to getAccumulator*()
+		// won't have old values.
+		final double sampleTime = 1.0 / getGlobalSampleRate();
+		final double overSamples = 1 << getOversampleBits();
+		final double averageSamples = 1 << getAverageBits();
+		Timer.delay(sampleTime * overSamples * averageSamples);
+
 	}
 
 	/**