Reach nodes by unique name instead of long paths

Nodes a script uses through a path of several nodes are marked unique in their
scene and found with %Name. The search list is renamed SearchResults, and the
player row's nodes get their real types.

music_list_panel.gd

@@ -8,7 +8,7 @@ signal song_clicked(song_no: int)
 var _song_list_object: PackedScene = preload("res://SongRow.tscn")
 
 @onready
-var _rows: VBoxContainer = $ScrollContainer/MusicList
+var _rows: VBoxContainer = %MusicList
 
 
 ## Shows the songs in the playlist again, so it shows their latest state.