Fix MS TO measurement representation

* set proper flag when saving MS Timing Offset
* use gsm_subscriber's IMSI or lchan's name if bsc_subscriber is unknown
* add comments with spec reference
* store/display MS Timing Offset instead of raw Timing Offset field from
  RSL
* Compute MS Timing Offset [-63; 192] from Timing Offset field [0; 255],
  adjust structure gsm_meas_rep with proper type to store it

Change-Id: I7e003d23a6edb714c5f17688fd6a8edac131161d
Related: OS#1574
diff --git a/openbsc/src/utils/meas_vis.c b/openbsc/src/utils/meas_vis.c
index 316d203..77194de 100644
--- a/openbsc/src/utils/meas_vis.c
+++ b/openbsc/src/utils/meas_vis.c
@@ -200,7 +200,7 @@
 				  COLS-40, rxlev2dbm(lq->rx_lev), -110, -47,
 				  1, 2, FALSE, FALSE);
 	//IsVisibleObj(ms->ul.cdk) = FALSE;
-	snprintf(msu->label, sizeof(msu->label), "</%d>%1d<!%d> %3d %2u %2u %4u",
+	snprintf(msu->label, sizeof(msu->label), "</%d>%1d<!%d> %3d %2u %2d %4u",
 		 qual_col, lq->rx_qual, qual_col, pwr,
 		 ms->mr.ms_l1.ta, ms->mr.ms_timing_offset,
 		 now - msu->last_update);