made AEL 8-bit transparent; mainly the lexer was tossing chars with the...

made AEL 8-bit transparent; mainly the lexer was tossing chars with the hi-order bit set. Not nice. Also, allow @ in extension names, and a backslash, also.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89682 65c4cc65-6c06-0410-ace0-fbb531ad65f3