No mux on excessive subjobs?

[Selur]

Did a quick test myself an it seems to work fine with no side effects that I can spot.

a. Hybrid doesn't always use mkvmerge for muxing, but also ffmpeg.
b. Hybrid throws out attachments with 'application/octet-stream' type. (No this will not change, this is intended.)

-> Will think about it in case there ever comes a case where the current handling is a problem.
Atm. it still seems too much hassle to implement this without if having any real effect.

Cu Selut