Add one log row at a time and pad log times

The log rebuilt every row each time a point was given or taken. It now
adds just the new row, and shows times as 09:05:03 instead of 9:5:3.

tests/integration/test_main_window.gd

@@ -226,3 +226,17 @@ func test_show_answer_before_first_song_does_not_reveal_next_song() -> void:
 
     assert_str((_window.get_node("VBoxContainer/SoundtrackLabel") as Label).text) \
             .is_equal("????????")
+
+
+func test_log_adds_one_row_per_point_with_padded_time() -> void:
+    var log_box: VBoxContainer = _window.get_node("%Log").get_node("%LogVBoxContainer")
+    var crono: PlayerObject = _add_player("Crono")
+    await _play_first_song()
+
+    crono.add_point()
+    crono.minus_point()
+
+    assert_int(log_box.get_child_count()).is_equal(2)
+    var time_pattern: RegEx = RegEx.create_from_string("^\\d\\d:\\d\\d:\\d\\d Crono got a point$")
+    assert_object(time_pattern.search((log_box.get_child(0) as Label).text)).is_not_null()
+    assert_str((log_box.get_child(1) as Label).text).ends_with("Crono lost a point")