Code objects list in programmer reversed compared to canvases

[juliendorra]

Canvas for new code objects are added on top of previous canvases.

But new code objects are listed at the bottom the list! This might be counter-intuitive, especially to users who are not aware of the internals of Paysage render-side.

We have 2 opposing UI metaphors possible:

• A text/paper list of things, where you add at the newest thing at the bottom (used now)
• A list of graphic layers, as in Photoshop for example. The top-most layer is added at the top, the list is in the same order as the canvas are.

We could change and try the layer list UI metaphor and see if it's better for making sense of the pile of visuals in bigger groups (class, workshop).

[juliendorra]

Fixed by #86