[ImGUI] Change selection display layout

[bakpaul]

I was tired of the fact that sometime a click will cover the part of the graph I am interacting with. So I put the graph on the left and added the object inspection on the right.

Currently it is in a state where you cannot open it in another way then by clicking on a object, click that will always open it.
If you close it it will deselect the node.

Another strategy would be to make it as any panel, so we could draw it or not by selecting it in the window menu, and if no object is selected the tab says that you need to select one. But I don't like it for two reason :

1. When you close the GUI while an object is selected, next time you open it you'll see the inspector empty with the message.
2. People might completely miss it if they don't know they can select it.

And I like the responsiveness of it.

[damienmarchal]

+1 for adding inspector on the right side.

[hugtalbot]

Nice ! It's starting having "de la gueule" !