Track selection improvements

[vertigo220]

When demuxing multiple files, it can be time-consuming selecting/deselecting the various tracks. In addition to allowing sorting per #453, which would make this easier as the tracks could be sorted by type, there are a few other improvements that would make this process easier:

1. Allow selecting/deselecting all tracks based on type, i.e. select/deselect all video tracks, audio tracks, and subtitle tracks.
2. Make pressing the space bar check/uncheck the highlighted track, which would allow for quickly going through the tracks with the arrow keys and hitting space to toggle them.
3. Allow selecting/deselecting all tracks based on language, e.g. deselect all tracks that aren't either eng or und (and, ideally, this would be a setting to do by default, so whenever files are added, any tracks not matching selected languages would automatically not be selected).

[jcdr428]

@vertigo220 hitting space to toggle highlighted track is already implemented.

[vertigo220]

Then maybe there's a bug, because it doesn't work for me. Just tried the latest version.

[jcdr428]

What OS are you on ?

[vertigo220]

Win10