RFC 6: Overall cleanups again.
RFC 6: Overall cleanups again.

- License should be fixed now (finally)
- Added doxygen comments
- Cleaned up the X11Grab structure
- Renamed X11Grab structure to x11_grab_s
- Changed some Java stylish named functions to more C'stylish ones
- Changed order of some parameters so they are more libc alike with
  destination as first parameter
- Use AVRational where relevant
- Fixed time calculation
- Cleaned up a few little tiny things around the sources
  + removed a goto
  + removed unused vars
  + etc...

git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@7299 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg