ActionFeedBack generates to many OpenGL lists

[davidebazzi]

I think that the class ActionFeedBack generates to many OpenGL lists.
Debugging an action that is using it to display faces as selected was very slow to rotate the view.
I saw in the output windows of visual studio many many calls of "Delete List."

CADability/CADability.Forms/PaintToOpenGL.cs

Line 2171 in 71b7ea4

System.Diagnostics.Debug.WriteLine($"Delete List. Count:{openLists.Count}");

Initially I only commented the above line of code, ad it was already a lot better.
Then I digged a little more and I saw that a new list is opened for each selected object

CADability/CADability/ActionFeedBack.cs

Line 82 in 71b7ea4

paintTo3D.OpenList("feedback");

And that there is a loop on all the views but the view object vw is never used

CADability/CADability/ActionFeedBack.cs

Line 61 in 71b7ea4

foreach (IView vw in frame.AllViews)

1. I think that is it enough to create a single list for all selected object
2. I think the loop on the View is unecessary

@SOFAgh , @dsn27 what do you think?