Backwards compatibly, introduce timer groups in OsmoBSC, and move some
non-specified T timers to new X timers:
T993111 -> X3111
T993210 -> X3210
T999 -> X4
Why X4? because there already is an X3 used elsewhere in Osmocom, and I find
it less confusing if X-numbers don't repeat across programs. See
https://osmocom.org/projects/cellular-infrastructure/wiki/List_of_Timer_numbers
Drop unused timers from g_mgw_tdefs. Only X2427 has an actual effect.
(libosmo-mgcp-client recently moved T2427001 to X2427.)
Put libosmo-mgcp-client related timers to the 'mgw' group, like in osmo-msc.
This makes the MGCP timeout configurable for the first time.
Keep previous timer commands as DEFUN_HIDDEN, and also translate the moved T
timers to X timers on-the-fly. All previous VTY commands still work, and new
'timer [(net|mgw)] ...' commands are added. timer.vty shows this.
Remove the "_OPTIONAL" from the legacy "timer" and "show timer" commands, so
that they don't ambiguously overload the new "timer [(net|mgw)] ..." commands.
Related: OS#4539
Related: If097f52701fd81f29bcca1d252f4fb4fca8a04f7 (osmo-mgw)
Change-Id: I4beec47502afa193dee343869c4be55dc6a4b536
638eb99286