ENCONT ( point, entity, enclos, ifail )
=======================================

  Enquire containment of point

Receives:
  KI_tag_point             *point          --- point
  KI_tag_entity            *entity         --- entity

Returns:
  KI_cod_encl              *enclos         --- enclosure code
  KI_cod_error             *ifail          --- failure code

Specific errors:
  KI_unsuitable_entity      can't do test on invalid entity
  KI_wrong_entity           'entity' of wrong type
  KI_general_body           general body

Description:

  Determines whether the point lies inside, outside or on the boundary of
  the entity.

  The point must be a geometric point, not a vertex. The entity must be a face,
  edge, shell, body or assembly. The entity must check, if it doesn't the
  result may be incorrect.

  The enclosure code will be one of:

      ENCLIN    inside
      ENCLOU    outside
      ENCLON    on (the limits of)

  The meaning of the three possible returns is obvious in most cases, but note
  the following:

    o For an edge, a point that is outside may lie on the curve but outside the
      limits of the edge, or may not lie on the curve at all. Similarly for a
      face and its surface.

    o For a face with holes, the interior of a hole is outside the face and the
      boundary of a hole is part of the boundary of the face.

    o For a shell, the inside is the portion of space that is full of material;
      i.e. if the shell is the exterior of a body, any point within the body
      is inside the shell, even if it lies in a void of the body. With respect
      to a void (interior) shell, points within the void are outside the shell.

    o For a solid body with voids, points within a void are outside the body and
      the boundaries of the interior shells are part of the boundary of the body.

    o For a sheet body, points are inside if they lie in the faces of the body,
      and on if they lie on edges or vertices on the boundary of the sheet.

    o For a wire body, points are inside if they lie on the wire, and on if they
      lie on a terminating vertex of the wire.

    o For an assembly, a point is inside if it is inside one or more of the
      body occurences in the assembly; it is on the boundary if it is inside
      no body occurence but is on the boundary of one or more body occurences;
      otherwise it is outside.

  This function is not supported for general bodies, shells in general
  bodies, or assemblies which contain a general body.