split mss_settings.json.sample into snippet parts

[Reimar Bauer]

Some not common features which are rare used and often won't be configured in a users mss_settings.json should be moved to snippet.

e.g. loop_configuration

"traj_nas_lon_identifier": ["GPS LON", "LONGITUDE"], "traj_nas_lat_identifier": ["GPS LAT", "LATITUDE"], "traj_nas_p_identifier": ["STATIC PRESSURE"]

[Reimar Bauer]

snippets and docu for rare used mss_settings tools, fixes #194

→ <<cset 061b352f36c4>>