DETGEO ( topol, ifail )
=======================

  Detach geometry from topology

Receives:
  KI_tag_topology          *topol          --- topology to detach from

Returns:
  KI_cod_error             *ifail          --- failure indicator

Specific errors:
  KI_no_geometry            no geometry attached
  KI_wrong_entity           illegal topology

Description:

  If 'topol' has geometry attached to it, the geometric entity is detached.
  The detached geometric entity is not deleted by DETGEO.

  The operations performed by DETGEO are:

      o Detach a surface from a face
      o Detach a curve from an edge
      o Detach a curve from a fin
      o Detach a point from a vertex
      o Detach a transform from an instance