Adding cut tube to the surface model

This MR adds the cut tube to the surface model.

The cut tube consists of two cylindrical surfaces (outer and inner tube), the end caps at the top and the bottom, and two planes for a possible phi cut. The end caps are represented as windows that encompass the elliptical surface. As a consequence, the cut tube must be a logical solid. Currently the phi cap planes are simple windows with and height equal to the maximum height of the cut tube (thus it could be significantly larger than it needs to be). For the future, these phi cap planes can be replaced by quadrilaterals that have exactly the maximum needed size.

Two GDMLs are added for testing, one with an inner radius of 0 and a phi cut < 180 degrees and a second one with an inner radius > 0 and a phi cut > 180 degrees.

Note a possible caveat: if the cut tube due to a large theta angle in the cut exceeds the world size, the simulation can crash. Currently, no assert is included and it is up to the user to define a reasonable geometry.