Move call answering stuff into new setsubstate_connected. Also add sub->substate var and set it to SUBSTATE_CONNECTED in setsubstate_connected.

(closes issue #17772)
Reported by: wedhorn
Patches:
      cleanup.stateconnected2.diff uploaded by wedhorn (license 30)
Tested by: wedhorn, salecha

Review: NA 


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@281227 65c4cc65-6c06-0410-ace0-fbb531ad65f3