Core/Movement: Compute current position in spline::Launch with Z offset. Fixes e.g. hovering creatures height increasing every time player interacts with it.

src/server/game/Movement/Spline/MoveSplineInit.cpp

@@ -58,7 +58,7 @@ namespace Movement
     {
         MoveSpline& move_spline = *unit.movespline;
 
-        Location real_position(unit.GetPositionX(),unit.GetPositionY(),unit.GetPositionZ(),unit.GetOrientation());
+        Location real_position(unit.GetPositionX(),unit.GetPositionY(),unit.GetPositionZMinusOffset(),unit.GetOrientation());
         // there is a big chane that current position is unknown if current state is not finalized, need compute it
         // this also allows calculate spline position and update map position in much greater intervals
         if (!move_spline.Finalized())