Official MPD clarification

[Travis Cobbs]

I think SR3D Builder will happily load an MPD file, but then lose all MPD-specific information (flatten the file, basically). I think that is part of the reason it has its own file extension, even though the files are basically just LDraw files. (Its files may also contain flexible part definitions that don't work elsewhere.)

I agree that MPD support should be strongly recommended, though.