Customize envelopper in MBC: for CargoImp Format

The current enveloper(s) for any EDI format (EDIFACT and X12) is only available as an MBC.The requiremen of different enveloping criteria other than what are available in the standard enveloper could be needed.

The CARGOIMP format has been introduced in Integrator v211 patch "ICARGOIMP_100-01-15"