Added Slicing the model in 3D Viewer

[t0mhw]

I added a very rudimentary function to enable slicing in the 3D Viewer. For example to view only half of a scan.

Using the 3D Rendering Tools Tab you can enable slicing, move a center Point by using 3 Sliders, one for each axis, and two sliders for a plane that seperates the model.

It worked for my use case but it's not perfect, partially because of my limited understanding of the code base. I'm happy to add changes to it if you have any suggestions where I could take a look at.

[nroduit]

Thank you for your contribution. It is indeed a feature that is part of the todo list. Initially the idea was to have a graphical clipping box tool, like in Slicer3D.

I'd also like to add a tool for cutting in 3 directions and according to the position and orientation of the crosshair in the MPR.

When enabled, these 2 tools would have to be manipulated directly on the image.