Feature #2193: write osmo-gsm-tester test cases and extend tester API
osmo-gsm-tester: add test case: smpp: smpp_first feature
Test feature "smpp_first" from smpp vty. When this feature is on, it will always first send the SMS to the ESME and let it take decisions on routing.
See smpp_vty.c in libmsc (openbsc) for more details.
Improve VTY doc if required.