(API Change) Add colorspace info to obs_video_info

This was an important change because we were originally using an
hard-coded 709/partial range color matrix for the output, which was
causing problems for people wanting to use different formats or color
spaces.  This will now automatically generate the color matrix depending
on the format, color space, and range, or use an identity matrix if the
video format is RGB instead of YUV.

obs/window-basic-main.cpp

@@ -1352,6 +1352,8 @@ int OBSBasic::ResetVideo()
 	ovi.output_height  = (uint32_t)config_get_uint(basicConfig,
 			"Video", "OutputCY");
 	ovi.output_format  = VIDEO_FORMAT_NV12;
+	ovi.colorspace     = VIDEO_CS_709;
+	ovi.range          = VIDEO_RANGE_FULL;
 	ovi.adapter        = 0;
 	ovi.gpu_conversion = true;