vty: Document some previously undocumented parameters

Katerina pointed out that some nodes are not fully documented and
proposed some messages. The token/timeout messages were correct, I
have modified the other messages. I removed the full-stop from the
PING/PONG documentation as we are normally not using a full sentence.
doc: Do not have examples with accept-all in our repository

We do not want to tell random users to run a network with the
accept-all. This was pointed out by Katerina.
bsc: Stop "show paging" from crashing before the first paging

The paging structure is still initialized lazily and we attempt
to traverse it before it is ready. The crash was discovered by
Katerina. Removing the lazy initialization will take a bit of work
as the gsm_data_shared is used by the osmo-bts and the OpenBSC but
paging is different.
bsc_vty: Prevent printing -1 as unsigned integer for timeslot TSC
rsl: Properly initialize the cm structure with memset

abis_rsl.c:332:23: warning: 'memset' call operates on objects of type 'struct rsl_ie_chan_mode'
      while the size is based on a different type 'struct rsl_ie_chan_mode *'
      [-Wsizeof-pointer-memaccess]
        memset(cm, 0, sizeof(cm));
               ~~            ^~
abis_rsl.c:332:23: note: did you mean to dereference the argument to 'sizeof' (and multiply it
      by the number of elements)?
        memset(cm, 0, sizeof(cm));
                             ^~
1 warning generated.
si: Another round of PCS related fixes

Inside the SI1 rest_octets we will need to indicate if the ARFCN
is band 1800 or 1900. If the BTS is either 850 or 1900 we assume
we are running a PCS network, otherwise it is a DCS network.

The band indicator is not documented in GSM 04.08 but it is in the
GSM 05.14 version 6.1.0 Release 1997.
BTS: Add S counter for link loss criterion to lchan structure
IPA: Allow RSL connection to different IP address as OML

This patch adds a new VTY command "ip.access rsl-ip A.B.C.D" at the
BTS level.  If you set this IP address, the BTS will be instructed to
establish the RSL link to the indiciated IP address, rather than using
the same as for the OML link (default).

Use "ip.access rsl-ip 0" to disable the feature.
SMPP: Fix crash on delivery of incoming SUBMIT-SM

As bsc_gsmnet is NULL at the time we call smpp_openbsc_init(),
we later run into segfaults with subscribers that don't have a
subscr->net set.

However, we cannot delay smpp_openbsc_init() until after
bsc_bootstrap_network(), as we then fail to parse the SMPP specific
VTY/config file options...
SMPP: Implement SMPP Osmocom Estensions on MO-SMS

An ESME can now be configured in the VTY to enable osmocom-extensions,
which will add vendor-specific SMPP TLVs for RxLev/RxQual/ARFCN/IMEI and
transmit power to the SMPP DELIVER-SM message type.
Fix osmo-nitb build without libsmpp
Add VTY option to set GPRS network-control-order to enable MS measurements

In order to enable GPRS downlink measurements at mobile, the
network-control-order must be set to nc1.
db: Link to the VTY library for the vty_config_unlock symbol

Linking started to fail for me due the symbol coming from the
vty library and the db code not linking to it.
bsc-ctrl: Fix a potential memory leak on failed verification

It was possible that the tmp was strduped but not freed, e.g. when
the number of commas was not right. It would evenutally be freed at
the time the cmd is freed thanks to the talloc hierachy.
Introduced support for external python tests