Add an SGs interface (3GPP TS 29.118) to osmo-msc in order to support
SMS tunneling and Circuit Switched Fallback (CSFB)
Change-Id: I73359925fc1ca72b33a1466e6ac41307f2f0b11d
Related: OS#3615
Apply more concise logging categories in each main scope. The bulk goes to
msc_main.c, obviously, while tests and utils get a slimmed down bunch of
logging categories.
Change-Id: I969a0662ba273f3721b6820d02151b7a5b8014b8
Having all BSSAP related logs in the "DMSC" category is overly
generic, and dosn't provide useful granularity.
Change-Id: Id1e52dad03840dfd026fb23f3845a8771c8cc308