large rewrite of the extension matching code,

prerequisite to implement the specification defined yesterday.

While I have been using this code for months now, the change is large
so expect some instability.

Also the new specification (sorting extension by match length etc.)
is not implemented yet.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@25928 65c4cc65-6c06-0410-ace0-fbb531ad65f3