Added AverageWindEncoder.

Refactored AverageWindDecoder - it now implements MessageDecoder.
Refactored AverageWind - it now uses milliseconds and knots, instead of packed MMperSec and tenths of a second. It also exposes its attributes now.
Added (un)packAverageWindPeriod to AC35UnitConverter.
Added AverageWindDecoderTest.
issue #35 #36
#story[1095]

racevisionGame/src/main/java/network/Utils/AC35UnitConverter.java

@@ -85,4 +85,23 @@ public class AC35UnitConverter {
     }
 
 
+    /**
+     * Packs an average wind period, in milliseconds, into an int, in tenths of a second.
+     * @param periodMilliseconds Period in milliseconds.
+     * @return Period in tenths of a second.
+     */
+    public static int packAverageWindPeriod(long periodMilliseconds) {
+        return (int) (periodMilliseconds / 100);
+    }
+
+    /**
+     * Unpacks an average wind period, in tenths of a second, into an long, in milliseconds.
+     * @param periodTenthsOfSecond Period in tenths of a second.
+     * @return Period in milliseconds
+     */
+    public static long unpackAverageWindPeriod(int periodTenthsOfSecond) {
+        return (periodTenthsOfSecond * 100);
+    }
+
+
 }