switch to 'new' expression parser, remove support for old parser

provide parser files in source tree, so flex/bison are not need to build
update Makefile to use simpler techniques to build parser
update README to remove references to old vs. new parsers
remove version comparison tool used for flex/bison programs


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6420 65c4cc65-6c06-0410-ace0-fbb531ad65f3