CRCMPC ( nbcs, bcs, bc, ifail )
===============================

  Join B-curves into a single curve

Receives:
  KI_int_nitems            *nbcs           --- number of B-curves
  KI_tag_b_curve            bcs[nbcs]      --- array of B-curves

Returns:
  KI_tag_b_curve           *bc             --- B-curve
  KI_cod_error             *ifail          --- failure indicator

Specific errors:
  KI_curves_dont_meet       curves are not sequential
  KI_bad_curves             invalid curves for joining
  KI_insufficient_curves    insufficient curves to join

Description:
  This function creates a B-curve by joining together a sequence of
  B-curves.

  . At least two B-curves must be supplied ('nbcs' >= 2).

  . The supplied curves must be in the correct order, and the end of each curve
    (except the last) must coincide with the start of the next. The curves
    must not be closed.

  . The end of the final curve may coincide with the start of the first, in
    which case a closed B-curve will be made.

  . The supplied curves are unchanged by the operation.

  . The order of the resulting curve will be the maximum of the orders of the
    supplied curves.

  . If any of the supplied curves are rational, the resulting curve will
    be rational.