refactor: view constructors from App

src/view/chain.rs

@@ -8,6 +8,16 @@ pub struct ChainView<'a> {
     pub vertical: bool,
 }
 
+impl<'a> ChainView<'a> {
+    pub fn new (app: &'a App, vertical: bool) -> Self {
+        Self {
+            focused:  app.section == AppSection::Chain,
+            track:    app.tracks.get(app.track_cursor - 1),
+            vertical
+        }
+    }
+}
+
 impl<'a> Render for ChainView<'a> {
     fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
         let style = Some(if self.focused {