Added Knots <-> MMperSec conversions to AC35UnitConverter.

Removed redundant/unused conversions.
Documented all of the conversions, and renamed them to pack/unpackX, to match the API spec.
Updated/added some tests in AC35UnitConverterTest.
RaceStatus now contains a Bearing instead of a packed int bearing.
RaceStatus now contains wind speed in knots, instead of MMperSec packed.
This means that only RaceStatus decoder/encoder need to care about the bits-over-wire packed values.
issue #35 #36
#story[1095]

racevisionGame/src/main/java/visualiser/model/VisualiserRace.java

@@ -313,8 +313,8 @@ public class VisualiserRace extends Race implements Runnable {
 
         //Wind.
         this.setWind(
-                Bearing.fromDegrees(raceStatus.getScaledWindDirection()),
-                raceStatus.getWindSpeedKnots()  );
+                raceStatus.getWindDirection(),
+                raceStatus.getWindSpeed()  );
 
         //Current race time.
         this.raceClock.setUTCTime(raceStatus.getCurrentTime());