Corrections for properly work with H.323v2 (older) endpoints and other

Corrections for properly work with H.323v2 (older) endpoints and other
small fixes.

Interpret remote side H.225 version.

Corrections for H.323v2 endpoints:
don't start TCS and MSD before connect,
don't start TCS and MSD by accepting H.245 connection,
start TCS and MSD by StartH245 facility message.

Other fixes:
fix non zeroended remoteDisplayName issue, small fixes in call clearing
by closing H.245 connection, tcp keepalive introduced on TCP
connections (now is hardcoded, will be configurable in the future),
don't force H.245tunneling if FastStart is active, don't send Alerting
singal more than once per call.

(closes issue #18542)
Reported by: vmikhelson
Patches:
      issue18542-final-3.patch uploaded by may213 (license 454)
Tested by: vmikhelson

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@307396 65c4cc65-6c06-0410-ace0-fbb531ad65f3