Unlike the other arguments for the resize function, "range_in" does not
use the same format as in the frame props. A frame prop _Range=1 means
limited, while an argument range_in=1 means full range.
Aegisub will automatically override the YCbCr Matrix field of the
current file's Script Properties with the video's reported color space.
The FFMS2 provider guesses a color space for all videos, but we don't
do this for Vapoursynth. Thus, we now disable this overriding whenever
the colorspace isn't known.
Since FileNotFound exceptions don't abort the provider search, opening
an invalid path would show errors such as "vapoursynth not found" when
VapourSynth wasn't installed, even if VapourSynth wasn't selected as the
default video provider.
This default script will be executed to load any file whose file name
extension is not .py or .vpy .
The gui code for setting the default script is still a bit wonky as it
doesn't fit the rest of the preferences pages nicely, but it works for
now.