Extracts general data file handling behaviour into a new DataFile class from which specific *File classes can inherit. Reduces repetition in code and the test suite, which is also refactored in line with the changes
Renames the VlfDataFile to the more suitable VlfFile class. This breaks things
Refactors field names for datetime and Modified JD
Refactors the data field name tests
Adds a names method to the DataFile API to avoid accessing them via the attribute itself
Extracts the methods for datetimes, beginning and end of the dataset into the DataFile superclass
Extract the GoesFile subclass test suite to a new file and rename the original to reflect the contained class name