Create boundaries GUI : change feature's order in the GUI

Change the order of the features :

1. input mesh
2. contour mesh : the field has to be empty by default but we can choose a layer if disponible. If not we can create it, and the name would be ContourMesh. Make in sort that when we save the contour layer it as the same style that the contour created.
3. boundaries : the field has to be empty by default but we can choose a layer if it already exists. If not, we create it. Make in sort that the boundaries layer is not a temporary layer. and maybe it's here that the layer should be saved automatically in the GUI (button save ?)
4. output mesh : really necessary ? Currently, when we click on create, the mesh is loaded once again => that is not necessary (and the first mesh isn't visible anymore) and the boundary file is saved in the directory.