attached two patches, which allows to set or append an audio track via command line and modify the assigned name.
The first allows to replace a given Index (1..4) or append, if the index is larger than the amount of assigned audio streams.
In case that an additional video is appended later on, the audio assignments get lost. So the same behaviour as within the GUI.
The second allows to modify the assigned language using the short code. Same index values are used
To avoid forgetting the language, it is possible to list all known languages and the short version of them
Note: this patch changes the way, how the options are taken into account, as the argument needs two parameters.