ADD apparent wind for WindBarbsOnRoute

Change from true wind direction and speed to apparent wind direction
and speed as it is the conditions that we have on the boat...
For example, it helps to see if we can do upwind or not.

src/RouteMapOverlay.cpp

@@ -725,14 +725,13 @@ void RouteMapOverlay::RenderWindBarbsOnRoute(wrDC &dc, PlugIn_ViewPort &vp)
         wxPoint p;
         GetCanvasPixLL(&nvp, &p, it->lat, it->lon);
 
-        double VW = it->VW;
-        double W = it->W;
+        // Calculate apparent wind direction
+        float windDirection = heading_resolve(it->B - it->W);
+        float apparentWindSpeed = Polar::VelocityApparentWind(it->VB, windDirection, it->VW);
+        float apparentWindDirection = Polar::DirectionApparentWind(apparentWindSpeed, it->VB, windDirection, it->VW);
 
         // Draw barbs
-        g_barbsOnRoute_LineBufferOverlay.pushWindArrowWithBarbs(
-            wind_barb_route_cache, p.x, p.y, VW,
-            deg2rad(W) + nvp.rotation, it->lat < 0, true
-        );
+        g_barbsOnRoute_LineBufferOverlay.pushWindArrowWithBarbs(wind_barb_route_cache, p.x, p.y, apparentWindSpeed, deg2rad(positive_degrees(apparentWindDirection - it->B)) + nvp.rotation, it->lat < 0, true);
     }
     wind_barb_route_cache.Finalize();