Properly respect GOSUB_RESULT as to what to do with the master channel.

Previously, we would parse GOSUB_RESULT, but not actually do anything with it.
Also, allow GOSUB_RETVAL to be inherited back across a peer/master channel.

(closes issue #16687)
 Reported by: bklang
 Patches: 
       app_dial-preserve-gosub_retval.patch uploaded by bklang (license 919)
       (with modifications)

(closes issue #16686)
 Reported by: bklang
 Patches: 
       app_dial-respect-gosub_result.patch uploaded by bklang (license 919)
       (with modifications)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@244393 65c4cc65-6c06-0410-ace0-fbb531ad65f3