lwinput: Add VapourSynth Script Reader.

Currently, only support RGB24 and YUV422P8.
AviUtl/configure: Move vsscript into LIBS from DEPLIBS.
lwinput: Fix vertical flip of VapourSynth RGB24 input.
vslsmas: Update VapourSynth.h.
lwinput: More pixel format and color space supports for VPY reader.
lwinput: Move file extension checker into common directory.
vpy_input: Change license: MIT -> ISC.
vpy_input: Update for VapourSynth R19.
AviUtl/colorspace: Generalize function arguments more.
lwinput: YUV range is supposed to be detected properly now.
vpy_input: Get color range and space per frame.
common/video_output: YUV range is supposed to be detected properly at init.
vslsmas: YUV range is supposed to be detected properly now.
lsmashsource: YUV range is supposed to be detected properly now.
lwinput: Add option to enable VSScript.
vslsmas: Update the header file for VapourSynth R19.
lwinput: Remove dependency of vsscript.dll installation.
vpy_input: Cosmetics.
vpy_input: More cosmetics.
vpy_input: Fix the returned value when vsscript.dll is not found.