modify app_chanspy to use new gain option
reformat app_chanspy to match coding guidelines
add user-controlled volume adjustment to app_meetme (issue #4170, heavily modified to actually work on Zap channels)
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6519 65c4cc65-6c06-0410-ace0-fbb531ad65f3