Use NSDMIs where applicable

aegisub/libaegisub/common/cajun/writer.cpp

aegisub/libaegisub/common/charset_conv.cpp

aegisub/libaegisub/common/color.cpp

aegisub/libaegisub/common/log.cpp

aegisub/libaegisub/common/vfr.cpp

aegisub/libaegisub/include/libaegisub/cajun/writer.h

aegisub/libaegisub/include/libaegisub/charset_conv.h

aegisub/libaegisub/include/libaegisub/color.h

aegisub/libaegisub/include/libaegisub/log.h

aegisub/libaegisub/include/libaegisub/vfr.h

aegisub/src/ass_dialogue.cpp

aegisub/src/ass_dialogue.h

aegisub/src/ass_exporter.cpp

aegisub/src/ass_exporter.h

aegisub/src/ass_karaoke.cpp

aegisub/src/ass_karaoke.h

aegisub/src/ass_override.cpp

aegisub/src/ass_override.h

aegisub/src/ass_parser.cpp

aegisub/src/ass_style.cpp