Fix FRACK message from external redirects; handle outbound channels better

Fix FRACK message from external redirects; handle outbound channels better

This patch does the following:
 * It simplifies the Dial handling in CDRs. As a rule, the caller in a dial
   relationship is always the Party A. There was some logic present in the
   handling of the dial message that could, conceivably, pick the caller
   as Party A for the beginning of the dial and the peer as Party A for the
   end of the dial. This shouldn't have happened if the code in the bridging
   framework was doing its job; however, that was broken and it led to the
   FRACK. As it is, this code was overly ocmplex and not needed: the caller,
   if present, should always be Party A. Period.
 * It properly checks to see if a channel will continue on in the dialplan.
   ast_check_hangup - much like cake at the end - is a lie. It will tell
   you that you are hungup when you are not. Do not believe it.

   I would make this function tell the truth, but I'm nervous that we've been
   depending on it sitting on its throne of lies for far too long, and it would
   probably break lots of things. So I'm just checking the "internal" soft
   hangup flags, like everyone else.

(closes issue ASTERISK-22060)
Reported by: Mark Michelson

(issue ASTERISK-21831)
Reported by: Matt Jordan

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@394290 65c4cc65-6c06-0410-ace0-fbb531ad65f3