- Deprecate "call-limit" in chan_sip. No other channel driver enforces call-limits

  and we now have the groupcount system to implement call-limits in the dialplan. You
  can use the "setvar" option in realtime/sip.conf to set limits per device.

- Implement "callcounter" as a new option to enable the call counting we need to
  report device status to queue, manager and SIP subscriptions.

The call counter setting is now enabled in the code by setting the device call-limit
to 999. When we remove the call limit, we can simply enable this with a boolean
setting.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89554 65c4cc65-6c06-0410-ace0-fbb531ad65f3