Doughnut-shaped rooms are not supported

[brunopostle]

Floor faces are actually discarded and a new floor slab created from the outline of the room perimeter wall. This code doesn't have any understanding of doughnut shaped rooms.

In fact a doughnut-shaped room has two perimeters, and this situation isn't handled at all gracefully.

Similarly, the IfcSpace is extruded from the room perimeter, but it is boolean intersected with the cell, so there is some intermediate glitchyness here.

This bug doesn't effect the space boundary and structural item code, as this works with the faces in the cellcomplex.