Pictures with "Scrolls with Map" setting become misaligned when loading a savegame

[Ghabry]

Use "Show Picture" with "Scrolls with Map" attribute (so that the picture is constant to the map and scrolls away when you walk) and save.

When loading the picture is correctly positioned until fade-in is done and then jumps away.

[Ghabry]

Initializing old_map_x and old_map_y fixes it

diff --git a/src/game_picture.cpp b/src/game_picture.cpp
index 57d69bf7..591f92e8 100644
--- a/src/game_picture.cpp
+++ b/src/game_picture.cpp
@@ -28,8 +28,8 @@ constexpr int z_mask = (1 << 16);
 
 Game_Picture::Game_Picture(int ID) :
 	id(ID),
-	old_map_x(0),
-	old_map_y(0)
+	old_map_x(Game_Map::GetDisplayX()),
+	old_map_y(Game_Map::GetDisplayY())
 {
 	RequestPictureSprite();
 }