ffmpeg/ffserver work again when just capturing video from a live
  source and you are streaming feeds of different frame rates.
* Fix a segfault in argument processing
* Add handling for -vhook argument
* Add logic to call video hooks if any have been specified.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@1247 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b