Implement Generator Based Property Accessors

[dixonwhitmire]

Implement property accessors on x12 transactional models to simplify record streaming and iteration by unwinding the arbitrarily complex ASC X12 Hierarchical Levels. The properties will alleviate the complexity of fetching segments and fields with nested "for" loops

It may be preferable to unwind the hierarchy and return something like

[
 {"info_source": data,
   "info_receiver": data,
    "subscriber": data,
    "dependents": data 
  },
 {"info_source": data,
   "info_receiver": data,
    "subscriber": data,
    "dependents": data 
  },
  etc
]

The properties should utilize generator/yield semantics to support large data sets. Ideally the implementation should be general enough that it can be shared or plugged into each transaction set.