CRCYSU ( posn, axis, radius, cylind, ifail )
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  Create a cylindrical surface.

Receives:
  KI_vec_position           posn           --- position on axis
  KI_vec_axis               axis           --- axis direction
  KI_dbl_radius            *radius         --- cylinder radius

Returns:
  KI_tag_surface           *cylind         --- cylindrical surface
  KI_cod_error             *ifail          --- failure code

Specific errors:
  KI_radius_too_large       radius too large

Description:
  An unbounded cylindrical surface of radius 'radius' is created with an
  axis 'axis' which passes through 'posn'.

  The surface normal points away from the axis.