Thanks to Peter Olsson

Closes: MODSKINNY-3

         fix fxs features

This solves incorrect display on the phone.

BUT: this creates a delta because the SQL value and the value known by
the phone. I hope this doesn't break other things.

(NB: the original problem here was the unability to do an UPDATE inside
a SELECT callback)

- send SWITCH_MESSAGE_INDICATE_DISPLAY when ringing (after knowing calle
  info
- send call info when receiving SWITCH_MESSAGE_INDICATE_DISPLAY

The send SWITCH_MESSAGE_INDICATE_DISPLAY part doesn't work yet, because
partner channel is locked (have to find out why)

- wait for media before marking channel as answered
- set effective_caller_{id,name} before sending call info

- for incoming calls, go CS_ROUTING only when number is dialed.
  CS_HIBERNATE before
- start media when both side have answered

Also:
- send tone for UNALLOCATED_NUMBER and USER_BUSY
- if channel variables are not sufficent to set call info, ask the
  partner channel

And try to keep each file below 2000 lines

Based on chan-sccp-b (file src/sccp_labels.h)

         add more debug logging
         fix signaling status return code in ftdm_io