 [det]load_settings(File)
[det]load_settings(File)- undefined(+Action)
- Define how to handle settings that are not defined. When
error, an error is printed and the setting is ignored. whenload, the setting is loaded anyway, waiting for a definition.
If possibly changed settings need to be persistent, the application 
must call save_settings/0 
as part of its shutdown. In simple cases calling at_halt(save_settings) 
is sufficient.