Show estimated temporary disk space requirement

[LittleVulpix]

Since temporary data will be stored as .y4m (avisynth is not supported or used at the moment), it would be nice to know ahead of time +- how much disk space is required for them. Splitting a somewhat short 1080p content can result in hundreds of gigabytes of data as .y4m is completely uncompressed, so it's easily possible for someone to fill their disk if they decide (god for bid) to encode something longer.

At any rate, thanks for this tool, it seems to be working really well ( threadripper user :D ) for some AV1 testing!