Typo correction
Adds a method to extract data between a start and end datetime
Adds the modified Julian Date fields to the data table
Refactors the functions use to fill new columns to reduce repetition
Calculates a float Julian Date based on the two data columns for day and seconds
Adds some documentation to the datetime string generator method
Adds Julian Date calculation to the Datetime module
Uses the new Julian Date method in the GoesFile class
Refactors the test suite to reduce repetition. Extracts common functionality and constants
Adds sorting by modified Julian Date column to combined data file. File order in the list doesn't matter now, I hope