Adding the ability to specify the To: header in an outbound INVITE

by adding an exclamation mark to the dial string.

This patch also exists for 1.4 in the fixtoheader-1.4 branch
and has been in production for quite some time.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@93897 65c4cc65-6c06-0410-ace0-fbb531ad65f3