toCCi -- construct an interval

• Usage:

  I = toCCi(n)

  I = toCCi(re,im)

  I = toCCi(prec,re,im)

• Inputs:
  • n, a complex number,
  • re, a real interval,
  • im, a real interval,
  • prec, an integer,
• Outputs:
  • I, a complex interval,