Added central compatibility header file, which enables blender to compile
against very old ffmpeg versions as well as very new versions using the
*NEW* API. (Old API functions are simulated using macros and inline functions)
Added a whole lot of additional checks, tested against 6 different versions
down the timeline, hopefully, now finally all is well.
* bring back 'player' libtype, after investigation with ideasman.
scons/mingw works nicely, for some reason msvc fails to link still, will look further into it.
* add jack support for audio system.
Note that for OSX jack support is still off by default, since
I'm not sure about what goes where. OSX maintainers, please check and fix.