== Core modules ==
The nasal root folder (FGDATA/Nasal/) is scanned for .nas files and these files are loaded (apparantly in alphabetical order).
After all .nas files are loaded
'''/sim/signals/nasal-dir-initialized ''' is set, which triggers listeners in some of the files just loaded.
This allows to use functions from other core files, which have just been defined, e.g. which were not yet available when parsing the file.
== Optional (load-once) modules ==