fix parallel building in the debian package: ffmpeg at least was only building serially before
allow user to specify ffmpeg options from either or both the
ffmpeg_options file and arguments to the scripts/ffmpeg-config script
debian package: build-depend and enable libmp3lame and libx264 in ffmpeg
add note to package description about what this package is and where it came from
update debian changelog
add notes about non-free codecs to README.debian
Merge remote-tracking branch 'origin/pr/18'