Add const

Author: ufechner7

examples_3d/parking_4p.jl

@@ -28,7 +28,7 @@ set.linear_solver="GMRES"       # GMRES, LapackDense or Dense
 STEPS = 352
 PRINT = false
 STATISTIC = false
-PLOT=false
+const PLOT=false
 UPWIND_DIR2       = -pi/2+deg2rad(10)     # Zero is at north; clockwise positive
 ZOOM = true
 FRONT_VIEW = true