Move Y position, height, and minimized state into TrackView...

... and eliminate some unnecessary calls to SubstitutePendingChangedTrack,
because the track and the substitute store Y and height in their shared
TrackView object.

Also make GetMinimizedHeight() virtual to avoid inclusion of TrackPanel.h in
TrackView.cpp.

src/LabelTrack.cpp

@@ -126,11 +126,6 @@ LabelTrack::LabelTrack(const std::shared_ptr<DirManager> &projDirManager):
    SetDefaultName(_("Label Track"));
    SetName(GetDefaultName());
 
-   // Label tracks are narrow
-   // Default is to allow two rows so that NEW users get the
-   // idea that labels can 'stack' when they would overlap.
-   SetHeight(73);
-
    ResetFont();
    CreateCustomGlyphs();