More PowerEntry work.

src/engine/wpak/data/PowerAction.java

@@ -15,7 +15,7 @@ public class PowerAction {
     public String effect_id;
     public int minTrains;
     public int maxTrains;
-    public int duration;
+    public float duration;
     public String stackingCategory;
     public mbEnums.CompoundCurveType curve;
     public int stackingPriority;