* Update SubfleetImporter.php
Correction to the import to include Simbrief Code
* Update SubfleetImporter.php
Added in the missing fields HUB-ID and SIMBrief as these are input on the main screen
* Update AircraftImporter.php
Part of the missing data fields in csv import export
* Update FlightImporter.php
Part of the missing fields in csv import and export
* Update AircraftImporter.php
* Update FlightImporter.php
* Update aircraft.csv
Test data amended as part of the missing csv fields
* Update subfleets.csv
Part of the fix for missing fields in csv files used for import/export
* Update flights.csv
* Update FlightImporter.php
* Update subfleets.csv
Removed unused fields
* Update FlightImporter.php
* Update FlightImporter.php
* Update FlightImporter.php
* amended for new csv file layouts
* Handle Route and Level fields too during import.
* Also removed the check for `visible => true` from `firstorNew` 'cause va admin may be importing to update not visible flights too.
(by default all new flights are visible, so no affect on new flights)
Closes#1201
* when importing flights, set subfleet name only if subfleet has been created, do not update existing subfleets
* add tests for flights import regarding subfleets
Co-authored-by: Andreas Palm <ap@ewsp.de>