ffmpeg: refactor to generic

* migrate some branches from ffmpeg.config.<optional>, now allows version specific configuration
* Added optionals for most features
* Added qt-faststart executable
* Licensing corrections
* Added dependencies
    + celt
    + faad2
    + flite
    + frei0r-plugins
    + fribidi
    + game-music-emu
    + gsm
    + jack2
    + ladspa-sdk
    + libavc1394
    + libbluray
    + libbs2b
    + libcaca
    + libmodplug
    + libogg
    + libraw1394
    + libssh
    + libwebp
    + libxcb
    + lzma
    + openal
    + opencl
    + opengl
    + openh264
    + openjpeg
    + openssl
    + pulseaudio
    + rtmpdump
    + samba
    + soxr
    + v4l-utils
    + vid.stab
    + wavpack
    + libX11
    + libXv
    + wavpack
    + x265
    + xavs
    + xvidcore
    + zeromq
* Outlines support for: (unpackaged/broken dependencies)
    + aacplus
    + avisynth
    + crystalhd
    + blackmagic-design-desktop-video
    + flite
    + ilbc
    + libavc1394
    + libcdio-paranoia
    + libiec61883
    + libmfx
    + libnut
    + nvenc (nvidia)
    + opencl
    + opencore-amr
    + openh264
    + oss
    + libquvi
    + schroedinger
    + shine
    + twolame
    + utvideo
    + vo-aacenc
    + vo-amrwbenc
    + zvbi