modularize src

+ merge main.py and manage.py
+ move start logic to swingmusic/__main__.py
+ add a run.py on the project root

swingmusic/lib/albumslib.py

@@ -0,0 +1,24 @@
+"""
+Contains methods relating to albums.
+"""
+
+
+from swingmusic.models.track import Track
+
+
+def remove_duplicate_on_merge_versions(tracks: list[Track]):
+    """
+    Removes duplicate tracks when merging versions of the same album.
+    """
+    # TODO!
+    pass
+
+
+def sort_by_track_no(tracks: list[Track]):
+    for t in tracks:
+        track = str(t.track).zfill(3)
+        t._pos = int(f"{t.disc}{track}")
+
+    tracks = sorted(tracks, key=lambda t: t._pos)
+
+    return tracks