wip: build arranger out of freestanding functions

app/src/model/model_scene.rs

@@ -8,7 +8,6 @@ impl Tek {
                 scene_color_1.mix(scene_color_2, i as f32 / n as f32).into()
             ))?;
         }
-        self.redraw_arranger();
         Ok(())
     }
     pub fn scene_add (&mut self, name: Option<&str>, color: Option<ItemPalette>)

app/src/model/model_track.rs

@@ -14,7 +14,6 @@ impl Tek {
                 track.width = width;
             }
         }
-        self.redraw_arranger();
         Ok(())
     }
     pub fn track_add (