make album column for tracks configurable

introduces new config variable `album_column`

fixes #267

src/playable.rs

@@ -76,8 +76,8 @@ impl ListItem for Playable {
         self.as_listitem().display_left()
     }
 
-    fn display_center(&self) -> String {
-        self.as_listitem().display_center()
+    fn display_center(&self, library: Arc<Library>) -> String {
+        self.as_listitem().display_center(library)
     }
 
     fn display_right(&self, library: Arc<Library>) -> String {