some more pass-through of WindLegTypeLegBearingCache for performance improvements; re-designed RankingMetric interface;

the new version of the interface returns a comparator for overall competitor ranking and a calculation for the time to improve
between a trailing and a leading competitor, determined in the trailing competitor's "time system." See bug 1018, comments
starting from #19.

java/com.sap.sailing.server/src/com/sap/sailing/server/masterdata/DummyTrackedRace.java

@@ -592,4 +592,14 @@ public class DummyTrackedRace extends TrackedRaceWithWindEssentials {
             WindPositionMode windPositionMode, WindLegTypeAndLegBearingCache cache) {
         return null;
     }
+
+    @Override
+    public Competitor getOverallLeader(TimePoint timePoint, WindLegTypeAndLegBearingCache cache) {
+        return null;
+    }
+
+    @Override
+    public List<Competitor> getCompetitorsFromBestToWorst(TimePoint timePoint, WindLegTypeAndLegBearingCache cache) {
+        return null;
+    }
 }