Partial extended multiplexing support

[Uight]

A partial implementation for extended multiplexing support.
It basically allows the parser to parse the lines and checks for correct syntax and delivers the data to the builder.
But in the builder nothing is done to the data. This is so the files with extended multiplexing can be parsed;

Due to all the discussions in earlier implementations of this i decided to try to implement it in smaller parts.
This part in particular shouldnt be controversial at all and just be mergable.

But then the question still remains how to truly handle the extended multiplexing data.

[EFeru]

Hi @Uight thanks for your contribuition. From my side it looks good.
@Adhara3 @Whitehouse112 any comments? (otherwise I merge).