FR: Track resizing

[fromwithin]

The folder tracks or submixes in the UI behave exactly like a normal track, expanding and shrinking with the Z key (or double-clicking), but this behaviour is really annoying as a folder has no operational benefit in being large (and as a side, looks really ugly when it is large and shows the block representation of the contained tracks).

I use the Z key a lot for expanding/shrinking tracks, but when I'm working I usually end up with a few folder tracks and I simply cannot stop from clicking on them, pressing Z and expecting them to open up instead of expand.

Therefore, I suggest the following behaviour:

• Folder tracks or submix tracks can never be expanded larger than the default track height (but can shrink smaller).
• Double-clicking on a folder track or submix track, or pressing Z while it is selected, does not resize it but instead opens or closes the track as if the user had clicked its little triangle on the left.