utils consolidations

[Reimar Bauer]

mswms.case_insensitive_multi_dict should be moved to mswms.utils

and may be

mslib.greatcircle to mslib.mss_util and that mss_util could also be renamed to utils

in both utils we should check if that all is used

[Joern Ungermann]

Partially addressed by 591dff0

[Reimar Bauer]

Refactored mss_utils

Moved utility stuff to mss_utils and renamed it more fittingly to just utils. Moved also the satellite_track loader to the sole place, where it is used.

Resolve issue #154

→ <<cset 9642614f4c51>>