ADVXED ( edge, point, newvrx, newedg, ifail )
=============================================

  Adds a new vertex to a given edge.

Receives:
  KI_tag_edge              *edge           --- edge to which vertex is added
  KI_vec_position           point          --- position vector for new vertex

Returns:
  KI_tag_vertex            *newvrx         --- new vertex added
 <KI_tag_edge>             *newedg         --- new edge added
  KI_cod_error             *ifail          --- failure code

Specific errors:
  KI_missing_geom           Edge not geometrically specified
  KI_not_on_edge            point not on edge curve
  KI_coincident             point coincident with existing vertex
  KI_unsuitable_entity      Mixed body

Description:
  The routine adds a new vertex to a given edge, with vertex geometry to
  suit the supplied vector.
  Adding a vertex to a ring edge, e.g. a complete circular edge,
  will not split the edge into two, whereas other remaining cases will.
  Tags of the new vertex, and where appropriate the new edge, will
  be returned from the routine.

  The routine will not allow the user to add a vertex to the edge
  where a vertex already exists, and will ensure that the new vertex
  lies within edge tolerance of the supplied edge.