Shared space for variables (instead of letting other channels muck with your own)

(closes issue #11943)
 Reported by: ramonpeek
 Patches: 
       20080208__bug11943__2.diff.txt uploaded by Corydon76 (license 14)
 Tested by: jmls


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@104098 65c4cc65-6c06-0410-ace0-fbb531ad65f3