Add some more IAX2-specific information about the channel to the CHANNEL()

function and begin the transition from SIPCHANINFO() to just using CHANNEL().
(closes issue #12856)
 Reported by: mostyn
 Patches: 
       iax_and_sip_channel_info.patch uploaded by mostyn (license 398)
       (with some additional cleanup by me)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@122802 65c4cc65-6c06-0410-ace0-fbb531ad65f3