feature: parse extra data available in Ulsterbus and Goldliner OpenDataNI ATCO-CIF files

[davidjrice]

Thanks to the work in #7 we can easily see unparsed data in the OpenDataNI dataset on Ulsterbus and Goldliner Timetable Data (last updated 8th November 2023).

The following record identifiers are not yet handled by the library and will be returned in the :unparsed resultant lines array.

• QD - Route Description
• QN - Journey Note
• QQ - Bus Operator Continuation
• QV - Vehicle Type

Each of these are documented in the ATCO-CIF spec but will need thought how to adapt the parsed data structure to make sense with their inclusion.