Visibility and flexibility of column mappings

[dandavies99]

Problem:

Currently the mappings for column titles used by the parsing engines are hard-coded and cannot be modified via the admin site or any other frontend method. It would be nice to be able to do this for more increased and visibility.

Proposed solution:

• Create a new "mapping" field on Parser (probably json or FK to totally separate model)
• Refactor the existing code to apply the mappings, because at the moment the code in parsing_engines/ doesn't have any knowledge of which Parser is being used. We'd probably have to pass it through from parse_data_file when it's called in the models.

Overall, it might be better to rethink the relationship between column headers and dfndb.Parameter objects. There is a one-to-one mapping of one to the other (SignalType) which is used in Parser. It might be better to be able to supply multiple column headings in a SignalType that map to one Parameter, which would cut out this additional step of mapping "actual column heading" to "intended column heading" within the parsing engines.

Aha! Link: https://imperial-college-ict.aha.io/requirements/RSE-138-13