Add incomplete matching to PBX code and app_dial

(closes issue #12351)
 Reported by: Corydon76
 Patches: 
       20080402__pbx_incomplete__3.diff.txt uploaded by Corydon76 (license 14)
       pbx_incomplete_with_timeout.diff uploaded by fabled (license 448)
 Tested by: Corydon76, fabled


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@114773 65c4cc65-6c06-0410-ace0-fbb531ad65f3