[fixes #468] Fixes rendering issue with freeform fins

Cause by a fencepost-error when generating body points for freeform fins on transitions.
Induced by the imprecision of floating point calculations.

core/src/net/sf/openrocket/rocketcomponent/FinSet.java

@@ -1095,6 +1095,13 @@ public abstract class FinSet extends ExternalComponent implements RingInstanceab
 			
 			xCur += increment;
 		}
+
+		// correct last point, if beyond a rounding error from body's end.
+		final int lastIndex = points.length - 1;
+		if( body.getLength()-0.000001 < points[lastIndex].x) {
+			points[lastIndex] = points[lastIndex].setX(body.getLength()).setY(body.getAftRadius());
+		}
+
 		return points;
 	}