Check if electrodes VTK is outside the pial surface but inside the skull

[mosenco]

During the execution of the algorithm #96, there is a case where the VTK are between the pial left and right and the algorithm detect it outside.

Obviously, after the insertions of electrodes inside the brain from the starting point to the target point, the electrodes will stay inside the skull and dont go out and in multiple time, during the insertion, so having the VTK and the fiducial labeled as outside is wrong.

We need a feature that tells whenever the electrodes are inside the skull but outside the pial surfaces

[mosenco]

Right now, if the electrodes are inside the skull but outside the pial surfaces, instead of the color white for the VTK and the symbol # for the fiducial point, the VTK will have a yellow color and the fiducial will have the $ symbol 0bdbab5