Report problem with rays exiting incorrectly from an optical element.

[ramezquitao]

Some of the optical elements in pyOpTools are being modeled by just using the optical surfaces, this means that in the edge or border of the element there are not limiting surfaces. When the system is behaving correctly, the ray enters crossing an optical surface and exits through an optical surface also. But it may happen the ray enters or exits the surface through the holes at the edges where no surface is defined. An error or at least a warning must be raised in such cases.